performselector

问题 As I understand there are several ways to send tasks to be performed in threads. The most common ones that I use are: 1) performSelector:withObject:afterDelay: 2) performSelectorOnMainThread:withObject:waitUntilDone: 3) performSelectorInBackground:withObject: 4) [NSThread detachNewThreadSelector:toTarget:withObject:] My first question is, what is the difference between 1) and 2), besides the obvious parameter differences? Are they actually both working in the Main thread (whose autorelease

问题 Below is a simple PerformSelector that sends a message to obj to perform the looping method. All works well but I get the following yellow warning. PerformSelector may cause a leak because its selector is unknown. #import "MyClass.h" #import <Foundation/Foundation.h> int main(int argc, const char * argv[]) { @autoreleasepool { MyClass *obj = [[MyClass alloc]init]; SEL mySel = @selector(looping); [obj performSelector:mySel]; } return 0; } This warning does not make sense because the

问题 i have implemented textToSpeech in my project and want to display an alertview while text is spoken. here i am calling the methods for textToSpeech: //-----before TTS starts i try to display alertView with Cancelbutton //[self performSelectorOnMainThread:@selector(alertWhileTTS) withObject:nil waitUntilDone:YES]; //gray view and no alertview //[self performSelector:@selector(alertWhileTTS)]; //gray view and no alertview //[self alertWhileTTS]; //gray view and no alertview //this part here is

问题 I couldn't find an answer anywhere else on the net so any help would be appreciated. I am tying to create a system whereby I can retrieve the results of an NSOperation task, which I understand cannot be done by concrete subclasses such as NSInvocation. I have an NSOperation subclass ( TheEngine ) which is abstract by convention and must be extended to implement the function -main , to include the body of code to execute. TheEngine contains the following initialisation function whose job is

问题 I have a function which takes a block as parameter: typedef void (^ MyBlock)(int); -(void)doTask:(MyBlock)theBlock{ ... } I need to run above function on another thread, I want to use - performSelector:onThread:withObject:waitUntilDone: , my current code: NSThread *workerThread = [[NSThread alloc] init]; [workerThread start]; [self performSelector:@selector(doTask:) onThread:workerThread withObject:??? waitUntilDone:NO]; BUT, How can I pass MyBlock parameter with this approach? (Please don't

问题 I want to change my UILabel 's text after 2 seconds. I tried setting my UILabel 's text to "A text" , and use sleep(2) and finally changing the text to "Another text" . But sleep(2) only freezes the app and "Another text" is set without displaying "A text" for 2 seconds. How may I display "A text" for 2 seconds and then show "Another text" ? 回答1: You can use [self performSelector:@selector(changeText:) withObject:text afterDelay:2.0]; or if you want to display it periodically, check the

问题 I am new to this iPhone app programming. I have a function with one argument type as structure pointer. This is shown below (void)responce:(structurePtr *)someData { ...... ...... } I want to call this function using performselector method after 5 seconds of time interval. Please tell me how to call above responce function using performselector Thanks in advance. 回答1: Use: - (void)performSelector:(SEL)aSelector withObject:(id)anArgument afterDelay:(NSTimeInterval)delay [yourObject

问题 Any reason why my label won't update? - (void)setLabel:(NSNotification*)notification { dispatch_async(dispatch_get_main_queue(), ^{ NSLog(@"setLabel"); [self.label setText:@"My Label"]; }); } I've also tried using performSelectorOnMainThread to no avail. Note that setLabel is appears on the log. Additional info: I also have two other functions which does the same thing but only with a different text. The two other functions doesn't have dispatch_async but they both work. Also, the

问题 I have an imageView added to a view that's presented as a modalViewController, with style horizontal flip. I have added the following code for animating the imageView. - (void)animateTheImageview:(UIImageView*) imageViewToAnimate{ CABasicAnimation *fadeAnimation; fadeAnimation = [CABasicAnimation animationWithKeyPath:@"opacity"]; fadeAnimation.duration = 1.5; fadeAnimation.repeatCount = INFINITY; fadeAnimation.autoreverses = NO; fadeAnimation.fromValue = [NSNumber numberWithFloat:1.0];

问题 I'm not sure how to use the API performSelector:onThread and I need some suggestions here. As far as I known, I need a runloop to make the call of performSelector:onThread , so I made one. But then I find a problem : once I called performSelector:onThread , the runloop stops. Here 's my test code, runloop is in function kickOffThread . - (void)setCurrentThread { self.thread = [NSThread currentThread]; } - (void)kickOffThread { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; [self