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2014/10/15 ¤U¤È 10:06:58
iphone Programming Glossary: dispatchHow do you trigger a block after a delay, like -performSelector:withObject:afterDelay:? http://stackoverflow.com/questions/4139219/how-do-you-trigger-a-block-after-a-delay-like-performselectorwithobjectafter but with an argument like int double float iphone objective c objective c blocks grand central dispatch share improve this question I think you're looking for dispatch_after . It requires your block to.. c blocks grand central dispatch share improve this question I think you're looking for dispatch_after . It requires your block to accept no parameters but you can just let the block capture those.. instead. int parameter1 12 float parameter2 144.1 Delay execution of my block for 10 seconds. dispatch_after dispatch_time DISPATCH_TIME_NOW 10 NSEC_PER_SEC dispatch_get_main_queue ^ NSLog @ parameter1 d..
Do you need to create an NSAutoreleasePool within a block in GCD? http://stackoverflow.com/questions/4141123/do-you-need-to-create-an-nsautoreleasepool-within-a-block-in-gcd run on a non main thread That is do you need to create an NSAutoreleasePool within each block you dispatch to anything other than the main queue In my limited testing I don't see the console warnings for autoreleased.. if someone could point out where this is stated. iphone objective c cocoa osx grand central dispatch share improve this question Does the same rule apply to a block that is placed within a Grand Central.. run on a non main thread That is do you need to create an NSAutoreleasePool within each block you dispatch to anything other than the main queue Grand central dispatch will manage an autorelease pool per queue..
Is there a way to make drawRect work right NOW? http://stackoverflow.com/questions/4739748/is-there-a-way-to-make-drawrect-work-right-now do this under Snow Leopard and iOS 4.0 is to use blocks like in the following rudimentary sample dispatch_queue_t main_queue dispatch_get_main_queue dispatch_async queue ^ Do some work dispatch_async main_queue.. and iOS 4.0 is to use blocks like in the following rudimentary sample dispatch_queue_t main_queue dispatch_get_main_queue dispatch_async queue ^ Do some work dispatch_async main_queue ^ Update the UI The Do.. like in the following rudimentary sample dispatch_queue_t main_queue dispatch_get_main_queue dispatch_async queue ^ Do some work dispatch_async main_queue ^ Update the UI The Do some work part of the above..
CADisplayLink OpenGL rendering breaks UIScrollView behaviour http://stackoverflow.com/questions/5944050/cadisplaylink-opengl-rendering-breaks-uiscrollview-behaviour table view that's onscreen at the same time as the rendering. For this you can create a GCD serial dispatch queue and use it for all of your rendering updates to a particular OpenGL ES context to avoid two actions.. at the same time. Then within your CADisplayLink callback you can use code like the following if dispatch_semaphore_wait frameRenderingSemaphore DISPATCH_TIME_NOW 0 return dispatch_async openGLESContextQueue.. like the following if dispatch_semaphore_wait frameRenderingSemaphore DISPATCH_TIME_NOW 0 return dispatch_async openGLESContextQueue ^ EAGLContext setCurrentContext context Render here dispatch_semaphore_signal..
How do you trigger a block after a delay, like -performSelector:withObject:afterDelay:? http://stackoverflow.com/questions/4139219/how-do-you-trigger-a-block-after-a-delay-like-performselectorwithobjectafter after a delay like using performSelector withObject afterDelay but with an argument like int double float iphone objective c objective c blocks grand central dispatch share improve this question I think you're looking for dispatch_after . It requires your block to accept no parameters but you can just let the block capture.. an argument like int double float iphone objective c objective c blocks grand central dispatch share improve this question I think you're looking for dispatch_after . It requires your block to accept no parameters but you can just let the block capture those variables from your local scope instead. int parameter1 12 float.. just let the block capture those variables from your local scope instead. int parameter1 12 float parameter2 144.1 Delay execution of my block for 10 seconds. dispatch_after dispatch_time DISPATCH_TIME_NOW 10 NSEC_PER_SEC dispatch_get_main_queue ^ NSLog @ parameter1 d parameter2 f parameter1 parameter2 share improve this answer..
Do you need to create an NSAutoreleasePool within a block in GCD? http://stackoverflow.com/questions/4141123/do-you-need-to-create-an-nsautoreleasepool-within-a-block-in-gcd is placed within a Grand Central Dispatch queue and will be run on a non main thread That is do you need to create an NSAutoreleasePool within each block you dispatch to anything other than the main queue In my limited testing I don't see the console warnings for autoreleased objects that you normally see with background threads.. seem to find definitive documentation on this so I was wondering if someone could point out where this is stated. iphone objective c cocoa osx grand central dispatch share improve this question Does the same rule apply to a block that is placed within a Grand Central Dispatch queue and will be run on a non main thread That.. is placed within a Grand Central Dispatch queue and will be run on a non main thread That is do you need to create an NSAutoreleasePool within each block you dispatch to anything other than the main queue Grand central dispatch will manage an autorelease pool per queue automatically. However there are no guarantees as to when..
Is there a way to make drawRect work right NOW? http://stackoverflow.com/questions/4739748/is-there-a-way-to-make-drawrect-work-right-now be done back on the main thread. Perhaps the easiest way to do this under Snow Leopard and iOS 4.0 is to use blocks like in the following rudimentary sample dispatch_queue_t main_queue dispatch_get_main_queue dispatch_async queue ^ Do some work dispatch_async main_queue ^ Update the UI The Do some work part of the above could.. Perhaps the easiest way to do this under Snow Leopard and iOS 4.0 is to use blocks like in the following rudimentary sample dispatch_queue_t main_queue dispatch_get_main_queue dispatch_async queue ^ Do some work dispatch_async main_queue ^ Update the UI The Do some work part of the above could be a lengthy calculation.. way to do this under Snow Leopard and iOS 4.0 is to use blocks like in the following rudimentary sample dispatch_queue_t main_queue dispatch_get_main_queue dispatch_async queue ^ Do some work dispatch_async main_queue ^ Update the UI The Do some work part of the above could be a lengthy calculation or an operation that loops..
CADisplayLink OpenGL rendering breaks UIScrollView behaviour http://stackoverflow.com/questions/5944050/cadisplaylink-opengl-rendering-breaks-uiscrollview-behaviour see any interruption of the native scrolling behavior of a table view that's onscreen at the same time as the rendering. For this you can create a GCD serial dispatch queue and use it for all of your rendering updates to a particular OpenGL ES context to avoid two actions writing to the context at the same time. Then within your.. OpenGL ES context to avoid two actions writing to the context at the same time. Then within your CADisplayLink callback you can use code like the following if dispatch_semaphore_wait frameRenderingSemaphore DISPATCH_TIME_NOW 0 return dispatch_async openGLESContextQueue ^ EAGLContext setCurrentContext context Render here dispatch_semaphore_signal.. Then within your CADisplayLink callback you can use code like the following if dispatch_semaphore_wait frameRenderingSemaphore DISPATCH_TIME_NOW 0 return dispatch_async openGLESContextQueue ^ EAGLContext setCurrentContext context Render here dispatch_semaphore_signal frameRenderingSemaphore where frameRenderingSemaphore is..
NSThread vs. NSOperationQueue vs. ??? on the iPhone http://stackoverflow.com/questions/3041837/nsthread-vs-nsoperationqueue-vs-on-the-iphone tests clean organized and happily asynchronous. A Would subclass again iphone nsthread nsoperationqueue grand central dispatch share improve this question In general you'll get better mileage with NSOperationQueue . Three specific reasons You..
How do you trigger a block after a delay, like -performSelector:withObject:afterDelay:? http://stackoverflow.com/questions/4139219/how-do-you-trigger-a-block-after-a-delay-like-performselectorwithobjectafter withObject afterDelay but with an argument like int double float iphone objective c objective c blocks grand central dispatch share improve this question I think you're looking for dispatch_after . It requires your block to accept no parameters.. objective c objective c blocks grand central dispatch share improve this question I think you're looking for dispatch_after . It requires your block to accept no parameters but you can just let the block capture those variables from your.. from your local scope instead. int parameter1 12 float parameter2 144.1 Delay execution of my block for 10 seconds. dispatch_after dispatch_time DISPATCH_TIME_NOW 10 NSEC_PER_SEC dispatch_get_main_queue ^ NSLog @ parameter1 d parameter2 f parameter1..
Do you need to create an NSAutoreleasePool within a block in GCD? http://stackoverflow.com/questions/4141123/do-you-need-to-create-an-nsautoreleasepool-within-a-block-in-gcd queue and will be run on a non main thread That is do you need to create an NSAutoreleasePool within each block you dispatch to anything other than the main queue In my limited testing I don't see the console warnings for autoreleased objects that.. this so I was wondering if someone could point out where this is stated. iphone objective c cocoa osx grand central dispatch share improve this question Does the same rule apply to a block that is placed within a Grand Central Dispatch queue.. queue and will be run on a non main thread That is do you need to create an NSAutoreleasePool within each block you dispatch to anything other than the main queue Grand central dispatch will manage an autorelease pool per queue automatically. However..
Is there a way to make drawRect work right NOW? http://stackoverflow.com/questions/4739748/is-there-a-way-to-make-drawrect-work-right-now the easiest way to do this under Snow Leopard and iOS 4.0 is to use blocks like in the following rudimentary sample dispatch_queue_t main_queue dispatch_get_main_queue dispatch_async queue ^ Do some work dispatch_async main_queue ^ Update the UI.. under Snow Leopard and iOS 4.0 is to use blocks like in the following rudimentary sample dispatch_queue_t main_queue dispatch_get_main_queue dispatch_async queue ^ Do some work dispatch_async main_queue ^ Update the UI The Do some work part of the.. iOS 4.0 is to use blocks like in the following rudimentary sample dispatch_queue_t main_queue dispatch_get_main_queue dispatch_async queue ^ Do some work dispatch_async main_queue ^ Update the UI The Do some work part of the above could be a lengthy..
Can use AVCaptureVideoDataOutput and AVCaptureMovieFileOutput at the same time? http://stackoverflow.com/questions/4944083/can-use-avcapturevideodataoutput-and-avcapturemoviefileoutput-at-the-same-time to the session AVCaptureVideoDataOutput output output for 32BGRA pixel format with me as the delegate and a suitable dispatch queue affixed. to prepare for output I'll output 640x480 in H.264 via an asset writer NSDictionary outputSettings NSDictionary..
NSURLConnection and grand central dispatch http://stackoverflow.com/questions/5037545/nsurlconnection-and-grand-central-dispatch and grand central dispatch Is it advisable to wrap up NSUrlConnection in a gcd style blocks and run it on a low_priority queue I need to ensure that.. connection Should I just call the synchronous versions but wrapped in gcd blocks And if I want to cancel a call use 'dispatch_suspend' dispatch_async queue ^ NSString result self mySynchronousHttp someURLToInvoke If I need to cancel dispatch_suspend.. I just call the synchronous versions but wrapped in gcd blocks And if I want to cancel a call use 'dispatch_suspend' dispatch_async queue ^ NSString result self mySynchronousHttp someURLToInvoke If I need to cancel dispatch_suspend queue iphone..
Grand Central Dispatch (GCD) vs. performSelector - need a better explanation http://stackoverflow.com/questions/5225130/grand-central-dispatch-gcd-vs-performselector-need-a-better-explanation waitUntilDone is an Obj C wrapper to the GCD C syntax. I've been thinking of these two commands as equivalent dispatch_sync dispatch_get_main_queue ^ self doit YES self performSelectorOnMainThread @selector doit withObject YES waitUntilDone.. is an Obj C wrapper to the GCD C syntax. I've been thinking of these two commands as equivalent dispatch_sync dispatch_get_main_queue ^ self doit YES self performSelectorOnMainThread @selector doit withObject YES waitUntilDone YES Am I incorrect.. of documentation on them but have yet to see a definitive answer. iphone objective c multithreading ios grand central dispatch share improve this question performSelectorOnMainThread does not use GCD to send messages to objects on the main thread...
Can you use cancel/isCancelled with GCD/dispatch_async? http://stackoverflow.com/questions/5449469/can-you-use-cancel-iscancelled-with-gcd-dispatch-async you use cancel isCancelled with GCD dispatch_async I've been wondering can you use cancel cancelAllOperations .isCancelled with a thread you have launched with GCD.. void procedurallyBuildEnormousSpaceship user has clicked button to build new spaceship pleaseAbandonYourEfforts FALSE dispatch_async dispatch_get_global_queue DISPATCH_QUEUE_PRIORITY_HIGH 0 ^ self actuallyProcedurallyBuildInBackground as an aside.. user has clicked button to build new spaceship pleaseAbandonYourEfforts FALSE dispatch_async dispatch_get_global_queue DISPATCH_QUEUE_PRIORITY_HIGH 0 ^ self actuallyProcedurallyBuildInBackground as an aside it's worth noting..
CADisplayLink OpenGL rendering breaks UIScrollView behaviour http://stackoverflow.com/questions/5944050/cadisplaylink-opengl-rendering-breaks-uiscrollview-behaviour behavior of a table view that's onscreen at the same time as the rendering. For this you can create a GCD serial dispatch queue and use it for all of your rendering updates to a particular OpenGL ES context to avoid two actions writing to the.. to the context at the same time. Then within your CADisplayLink callback you can use code like the following if dispatch_semaphore_wait frameRenderingSemaphore DISPATCH_TIME_NOW 0 return dispatch_async openGLESContextQueue ^ EAGLContext setCurrentContext.. you can use code like the following if dispatch_semaphore_wait frameRenderingSemaphore DISPATCH_TIME_NOW 0 return dispatch_async openGLESContextQueue ^ EAGLContext setCurrentContext context Render here dispatch_semaphore_signal frameRenderingSemaphore..
Load image to a tableView from URL iphone sdk http://stackoverflow.com/questions/7565123/load-image-to-a-tableview-from-url-iphone-sdk image loading share improve this question You can use GCD to load images in background thread like this get a dispatch queue dispatch_queue_t concurrentQueue dispatch_get_global_queue DISPATCH_QUEUE_PRIORITY_DEFAULT 0 this will start the image.. share improve this question You can use GCD to load images in background thread like this get a dispatch queue dispatch_queue_t concurrentQueue dispatch_get_global_queue DISPATCH_QUEUE_PRIORITY_DEFAULT 0 this will start the image loading in.. You can use GCD to load images in background thread like this get a dispatch queue dispatch_queue_t concurrentQueue dispatch_get_global_queue DISPATCH_QUEUE_PRIORITY_DEFAULT 0 this will start the image loading in bg dispatch_async concurrentQueue..
Last In-First Out Stack with GCD? http://stackoverflow.com/questions/7567827/last-in-first-out-stack-with-gcd question as well as the best solution I ended up implementing... iphone objective c ios uitableview grand central dispatch share improve this question Because of the memory constraints of the device you should load the images on demand and.. check to see if your contact's image is nil or has been cached. If the image is nil or not in cache use a nested dispatch_async to load the image from the database and update the tableView cell. UITableViewCell tableView UITableView tableView.. reuseIdentifier CellIdentifier If the contact object's image has not been loaded Use a place holder image then use dispatch_async on a background queue to retrieve it. if contact.image nil cell imageView setImage contact.image else Set a temporary..
Correct Singleton Pattern Objective C (iOS)? http://stackoverflow.com/questions/7598820/correct-singleton-pattern-objective-c-ios return NSUIntegerMax That's soooo non zero MySingleton sharedInstance static MySingleton instance nil static dispatch_once_t predicate dispatch_once predicate ^ call to super avoids a deadlock with the above allocWithZone instance super.. That's soooo non zero MySingleton sharedInstance static MySingleton instance nil static dispatch_once_t predicate dispatch_once predicate ^ call to super avoids a deadlock with the above allocWithZone instance super allocWithZone nil init return.. missing something or doing something completely wrong Cheers Stefan iphone objective c ios singleton grand central dispatch share improve this question Keep it simple id sharedInstance static dispatch_once_t pred static MyClass sharedInstance..
UIStringDrawing methods don't seem to be thread safe in iOS 6 http://stackoverflow.com/questions/12744558/uistringdrawing-methods-dont-seem-to-be-thread-safe-in-ios-6 Exception Type EXC_CRASH SIGSEGV Exception Codes 0x0000000000000000 0x0000000000000000 Crashed Thread 0 Thread 0 name Dispatch queue com.apple.main thread Thread 0 Crashed 0 libsystem_kernel.dylib 0x3a28ee80 semaphore_wait_trap 8 1 libdispatch.dylib.. long long void 60 13 IOMobileFramebuffer 0x31221fd4 IOMobileFramebufferVsyncNotifyFunc 152 14 IOKit 0x39f7c5aa IODispatchCalloutFromCFMessage 190 15 CoreFoundation 0x39899888 __CFMachPortPerform 116 16 CoreFoundation 0x398a43e4 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__.. 0x35089284 UIApplicationMain 1116 23 myApp 0x000b806e main main.m 16 24 myApp 0x000b8024 start 36 Thread 7 name Dispatch queue com.myApp.SerialDrawQueue Thread 7 0 WebCore 0x35a21410 WebCore FontFallbackList invalidate WTF PassRefPtr WebCore..
iOS crash reports: atos not working as expected http://stackoverflow.com/questions/13574933/ios-crash-reports-atos-not-working-as-expected Type EXC_BAD_ACCESS SIGSEGV Exception Codes KERN_INVALID_ADDRESS at 0x51fe5264 Crashed Thread 0 Thread 0 name Dispatch queue com.apple.main thread Thread 0 Crashed 0 libobjc.A.dylib 0x352925b0 objc_msgSend 16 1 MYAPP 0x0006573a MyViewController..
XCode 5 Crashes on AppStore Validation http://stackoverflow.com/questions/18913964/xcode-5-crashes-on-appstore-validation 5941 sec Per App Crashes Since Last Report 8 Anonymous UUID B3570A30 11F9 5E70 9890 7B380C40FAE3 Crashed Thread 0 Dispatch queue com.apple.main thread Exception Type EXC_BAD_ACCESS SIGSEGV Exception Codes EXC_I386_GPFLT Application Specific Information.. Specific Information objc_msgSend selector name respondsToSelector ProductBuildVersion 5A1413 Thread 0 Crashed Dispatch queue com.apple.main thread 0 libobjc.A.dylib 0x00007fff91d39510 objc_msgSend_vtable5 16 1 com.apple.AppKit 0x00007fff8c52c3b2..
NSThread vs. NSOperationQueue vs. ??? on the iPhone http://stackoverflow.com/questions/3041837/nsthread-vs-nsoperationqueue-vs-on-the-iphone the work is already done for you. NSOperationQueue is free to switch to a smarter implementation like Grand Central Dispatch now or in the future. NSThread is more likely to always be just an operating system thread. Bonus NSOperationQueue has some..
iphone ios running in separate thread http://stackoverflow.com/questions/3869217/iphone-ios-running-in-separate-thread ios thread safety share improve this question In my opinion the best way is with libdispatch aka Grand Central Dispatch GCD . It limits you to iOS 4 and greater but it's just so simple and easy to use. The code to do some processing on a background..
Do you need to create an NSAutoreleasePool within a block in GCD? http://stackoverflow.com/questions/4141123/do-you-need-to-create-an-nsautoreleasepool-within-a-block-in-gcd or operation because none exists by default. Does the same rule apply to a block that is placed within a Grand Central Dispatch queue and will be run on a non main thread That is do you need to create an NSAutoreleasePool within each block you dispatch.. dispatch share improve this question Does the same rule apply to a block that is placed within a Grand Central Dispatch queue and will be run on a non main thread That is do you need to create an NSAutoreleasePool within each block you dispatch..
NSURLConnection and grand central dispatch http://stackoverflow.com/questions/5037545/nsurlconnection-and-grand-central-dispatch programming and recommended to use asynchronous network programming with RunLoop. Use background thread Grand Central Dispatch Concurrent Queue for thread safe data processing not for network programming. By the way Blocks and Grand Central Dispatch.. Concurrent Queue for thread safe data processing not for network programming. By the way Blocks and Grand Central Dispatch sessions are also worth to see. WWDC 2010 Session 206 Introducing Blocks and Grand Central Dispatch on iPhone WWDC 2010.. and Grand Central Dispatch sessions are also worth to see. WWDC 2010 Session 206 Introducing Blocks and Grand Central Dispatch on iPhone WWDC 2010 Session 211 Simplifying iPhone App Development with Grand Central Dispatch I wrote a wrapper class for..
How to make ui responsive all the time and do background updating? http://stackoverflow.com/questions/5133731/how-to-make-ui-responsive-all-the-time-and-do-background-updating grid of thumbnails. TIA Praveen S iphone objective c cocoa asynchronous share improve this question Grand Central Dispatch is easy to use for background loading. But GCD is only for after iOS4. If you have to support iOS3 performSelectorInBackground..
Grand Central Dispatch (GCD) vs. performSelector - need a better explanation http://stackoverflow.com/questions/5225130/grand-central-dispatch-gcd-vs-performselector-need-a-better-explanation Central Dispatch GCD vs. performSelector need a better explanation I've used both GCD and performSelectorOnMainThread waitUntilDone in my..
Building with LLVM and any optimization causes app to crash on startup http://stackoverflow.com/questions/5490432/building-with-llvm-and-any-optimization-causes-app-to-crash-on-startup Type EXC_BAD_ACCESS SIGBUS Exception Codes KERN_PROTECTION_FAILURE at 0x00b53400 Crashed Thread 0 Thread 0 name Dispatch queue com.apple.main thread Thread 0 Crashed 0 0x00b53400 0 11875328 It won't symbolicate correctly since it doesn't know..
CADisplayLink OpenGL rendering breaks UIScrollView behaviour http://stackoverflow.com/questions/5944050/cadisplaylink-opengl-rendering-breaks-uiscrollview-behaviour One way around this is to perform your OpenGL ES rendering actions on a background thread by using a Grand Central Dispatch serial queue. I did this in my recent update to Molecules source code for which can be found at that link and in testing..
Last In-First Out Stack with GCD? http://stackoverflow.com/questions/7567827/last-in-first-out-stack-with-gcd and then the others that are currently off screen would be updated. Is such a thing possible with Grand Central Dispatch Or not too onerous to implement some other way Note by the way that I am using Core Data with a SQLite store and I am not.. theCell setNeedsLayout return cell The WWDC2010 conference video Introducing Blocks and Grand Central Dispatch shows an example using the nested dispatch_async as well. another potential optimization could be to start downloading the..
Why does Apple recommend to use dispatch_once for implementing the singleton pattern under ARC? http://stackoverflow.com/questions/9119042/why-does-apple-recommend-to-use-dispatch-once-for-implementing-the-singleton-pat to create my object It doesn't return immediately right At least that seems to be the whole point of Grand Central Dispatch. So why are they doing this iphone objective c ios singleton automatic ref counting share improve this question dispatch_once..
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