如何阻止NSTimer

Question

嘿所以我只是做一个示例应用程序,我有一点麻烦,所以我有一个表视图,然后我有几行,当用户点击一行时,它将他们带到一个新的视图.在这个视图中,我有一个播放音乐的按钮.我正在使用计时器根据音乐持续时间和剩余时间增加滑块.

现在我的问题是,我需要做什么,以便当我通过左上角按钮返回表格视图时,NSTimer会停止？

这是我到目前为止,我不能重复:YES计时器停止.

#import "SecondViewController.h"

@implementation SecondViewController
@synthesize lbl1;
@synthesize timer;

-(IBAction) slide {
 myMusic.currentTime = slider.value;
}

-(IBAction)play
{
timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(updateTime) userInfo:nil repeats:YES];
 slider.maximumValue = [myMusic duration];
 myMusic.volume = 0.2;
 [myMusic prepareToPlay];
 [myMusic play];
}

-(IBAction)pause
{
 [myMusic pause];
}

-(IBAction)stop
{
 slider.value = 0;
 myMusic.currentTime = 0;
 [myMusic stop];
}

- (void)updateTime{
  slider.value = myMusic.currentTime;
}

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {

  //This plays music, we must give it a path to find the file and then u can change it. 
 NSString * pathToMusicFile = [[NSBundle mainBundle] pathForResource:@"Katy" ofType:@"mp3"];
     myMusic = [[ AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:pathToMusicFile] error:NULL];
     myMusic.delegate = self;
     myMusic.numberOfLoops = -1;

 slider.value = 0;
 //[myMusic play];

    [super viewDidLoad];
}


- (void)viewDidUnload {

 [timer invalidate];
 timer = nil;
 //myMusic.currentTime = 0;
 [myMusic stop];
 [super viewDidUnload];

 // Release any retained subviews of the main view.
 // e.g. self.myOutlet = nil;
}

-(IBAction) TxtChange;{

 lbl1.text = @" test2! I CHNAGED TEXT FROM ANOTHER XIB";
}

- (void)dealloc {
 [timer invalidate];
 timer = nil; 
 [myMusic release];
    [super dealloc];
}

@end

Answer 1

使用以下代码.它会工作但请记住,只有在我们的计时器处于运行模式时才能调用它,否则应用程序将崩溃.

- (void)viewWillDisappear:(BOOL)animated {
    //BEFORE DOING SO CHECK THAT TIMER MUST NOT BE ALREADY INVALIDATED
    //Always nil your timer after invalidating so that 
    //it does not cause crash due to duplicate invalidate
       if(timer)
       {
         [timer invalidate];
         timer = nil;
       }
    [super viewWillDisappear:animated];
}

Answer 2

像这样:

[yourtimername invalidate];

但要小心,如果计时器已经停止,你就不能停止计时器,因为你的应用程序会崩溃.

Answer 3

正如iCoder所说,它必须在viewWillDisappear中失效.

我添加了以下内容以确保.这个对我有用.希望它有所帮助(并添加到icoders回答不打算复制)

- (void) startTimer
{
[self stopTimer];
timer = [NSTimer scheduledTimerWithTimeInterval: 5.0
                                                     target: self
                                                   selector:@selector(onTick)
                                                   userInfo: nil repeats:YES];

}

- (void) stopTimer
{
    if (timer) {
        [timer invalidate];
        timer = nil;
    }

}

Answer 4

4岁的帖子,我知道,但也许我可以保存下一个人免于浪费时间尝试使NSTimer无效.苹果文档解释了它,它适用于我.

在.h

@property(nonatomic, retain) NSTimer *yourTimer;
@property(weak) NSTimer *repeatingTimer;

在.m

@synthesize yourTimer, repeatingTimer;

在viewDidLoad中

yourTimer = [NSTimer scheduledTimerWithTimeInterval:(NSTimerInterval)(40.0/60.0)
                                             target:self
                                           selector:@selector(blink)
                                           userInfo:nil
                                            repeats:TRUE];

  self.repeatingTimer = yourTimer;

在我的viewDidDisappear中

   [repeatingTimer invalidate];
   repeatingTimer = nil;

诀窍在于将第一个NSTimer分配给(弱)NStimer对象并杀死该对象.