2014/10/15 下午 10:12:32

iphone Programming Glossary: performselectoronmainthread

How to use UIProgressView while loading of a UIWebView?

http://stackoverflow.com/questions/1900151/how-to-use-uiprogressview-while-loading-of-a-uiwebview

that any time you manipulate a visible control from one of the NSURLConnection delegate methods you do so by calling performSelectorOnMainThread otherwise you'll start getting the dreaded EXC_BAD_ACCESS errors. Using this technique you can show a progress bar when..

Subclassing NSOperation to be concurrent and cancellable

http://stackoverflow.com/questions/3859631/subclassing-nsoperation-to-be-concurrent-and-cancellable

isCancelled _isCancelled BOOL isConcurrent return YES void start WHY SHOULD I PUT THIS if NSThread isMainThread self performSelectorOnMainThread @selector start withObject nil waitUntilDone NO return self willChangeValueForKey @ isExecuting _isExecuting YES self didChangeValueForKey.. @ isFinished if _isCancelled YES NSLog @ OPERATION CANCELED In the example I found I don't understand why performSelectorOnMainThread is used. It would prevent my operation from running concurrently. Also when I comment out that line I get my operations.. performselector share improve this question Okay so as I understand it you have two questions Do you need the performSelectorOnMainThread segment that appears in comments in your code What does that code do Why is the _isCancelled flag is not modified when you..

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

nil or self performSelectorInBackground @selector doWork withObject nil and then to update the UI you can use self performSelectorOnMainThread @selector updateProgress withObject nil waitUntilDone NO Note that I've found the NO argument in the previous method to..

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

to use for background loading. But GCD is only for after iOS4. If you have to support iOS3 performSelectorInBackground performSelectorOnMainThread or NSOperationQueue are helpful. And be careful almost UIKit classes are not thread safe except drawing to a graphics context...

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 apps and tend to think of them as interchangeable that is performSelectorOnMainThread waitUntilDone.. both GCD and performSelectorOnMainThread waitUntilDone in my apps and tend to think of them as interchangeable that is performSelectorOnMainThread waitUntilDone is an Obj C wrapper to the GCD C syntax. I've been thinking of these two commands as equivalent dispatch_sync.. 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 That is is there a difference of the performSelector commands..

GCD, Threads, Program Flow and UI Updating

http://stackoverflow.com/questions/7290931/gcd-threads-program-flow-and-ui-updating

UI from a background thread. If you're not using blocks and using performSelectInBackground then when you're done call performSelectorOnMainThread which calls a selector to update your UI. performSelectorInBackground Sample In this snippet I have a button which invokes.. simulate 5 seconds of work I added a slider to the form I can slide it back and forth during the 5 sec. sleep 5 self performSelectorOnMainThread @selector workDone withObject nil waitUntilDone YES void workDone id obj self feedbackLabel setText @ Done ... self doWorkButton..

Application crashed while importing songs from Ipod library in Iphone for iOs 5.0

http://stackoverflow.com/questions/8077725/application-crashed-while-importing-songs-from-ipod-library-in-iphone-for-ios-5

NSString str NSString stringWithFormat @ Loading d of d Beats totalcollection counterIpod totalcollection lbl performSelectorOnMainThread @selector setText withObject str waitUntilDone NO NSLog @ loading string @ str return NSLog @ file not exist int fileNumber.. counterIpod totalcollection self performSelector @selector setLabelText withObject str afterDelay 0.02 lbl performSelectorOnMainThread @selector setText withObject str waitUntilDone NO NSLog @ loading string @ str if counterIpod 0 self showAlertView self.. NSString str NSString stringWithFormat @ Loading d of d Beats totalcollection counterIpod totalcollection lbl performSelectorOnMainThread @selector setText withObject str waitUntilDone NO return NO if counterIpod 0 self showAlertView self hideLoadingView..

iOS 5 Attach photo to Twitter with Twitter API

http://stackoverflow.com/questions/8129079/ios-5-attach-photo-to-twitter-with-twitter-api

NSError error NSString output NSString stringWithFormat @ HTTP response status i urlResponse statusCode self performSelectorOnMainThread @selector displayText withObject output waitUntilDone NO I found using TWRequest to be best solution for my scenario as..