iOS中定時器NSTimer的使用

iOS中定時器NSTimer的使用

一、初始化

+ (NSTimer *)timerWithTimeInterval:(NSTimeInterval)ti target:(id)aTarget selector:(SEL)aSelector userInfo:(id)userInfo repeats:(BOOL)yesOrNo;

+ (NSTimer *)scheduledTimerWithTimeInterval:(NSTimeInterval)ti target:(id)aTarget selector:(SEL)aSelector userInfo:(id)userInfo repeats:(BOOL)yesOrNo;

注：不用scheduled方式初始化的，須要手動addTimer:forMode: 將timer添加到一個runloop中。

　　而scheduled的初始化方法將以默認mode直接添加到當前的runloop中.

 

舉例：

NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:10.0 target:self selector:@selector(timerFired:) userInfo:nil repeats:NO];

或

NSTimer *myTimer = [NSTimer  timerWithTimeInterval:3.0 target:selfselector:@selector(timerFired:)userInfo:nilrepeats:NO];

[[NSRunLoop  currentRunLoop] addTimer:myTimerforMode:NSDefaultRunLoopMode];

 

二、觸發（啓動）

當定時器建立完（不用scheduled的，添加到runloop中後，該定時器將在初始化時指定的timeInterval秒後自動觸發。

 

能夠使用-(void)fire;方法來當即觸發該定時器；

注：You can use this method to fire a repeating timer without interrupting its regular firing schedule. If the timer is non-repeating, it is automatically invalidated after firing, even if its scheduled fire date has not arrived.

在重複執行的定時器中調用此方法後當即觸發該定時器，但不會中斷其以前的執行計劃；

在不重複執行的定時器中調用此方法，當即觸發後，就會使這個定時器失效。

 

三、中止

- (void)invalidate;

這個是惟一一個能夠將計時器從runloop中移出的方法。

 

注：

NSTimer能夠精確到50-100毫秒.

NSTimer不是絕對準確的,並且中間耗時或阻塞錯過下一個點,那麼下一個點就pass過去了.

 

延時函數和Timer的使用

//延時函數： [NSThread sleepForTimeInterval:5.0]； //暫停5s. //Timer的使用： NSTimer *connectionTimer; //timer對象 //實例化timer self.connectionTimer=[NSTimer scheduledTimerWithTimeInterval:1.5 target:self selector:@selector(timerFired:) userInfo:nil repeats:NO];
[[NSRunLoop currentRunLoop]addTimer:self.connectionTimer forMode:NSDefaultRunLoopMode]; //用timer做爲延時的一種方法  do{
[[NSRunLoopcurrentRunLoop]runUntilDate:[NSDatedateWithTimeIntervalSinceNow:1.0]];
}while(!done); //timer調用函數 -(void)timerFired:(NSTimer *)timer{
done =YES;
}

 

轉自：http://magicalboy.com/objective_c_nstimer_usage/#comment-45

建立 NSTimer

1. Scheduled Timers & Using Selector

 

-  ( IBAction ) startOneOffTimer: sender  {

 

     [ NSTimer  scheduledTimerWithTimeInterval: 2.0

 

              target: self

 

              selector: @selector ( targetMethod: )

 

              userInfo: [ self  userInfo ]

 

              repeats: NO ];

 

}

view raw gistfile1.m This Gist brought to you by  GitHub.

 

如上，若是沒有重複執行的timer至關於 

[self performSelector:@selector(targetMethod:) withObject:nil afterDelay:2.0];

 

 

// declcare

@property  ( assign )  NSTimer  * repeatingTimer ;

 

// implements

-  ( IBAction ) startRepeatingTimer: sender  {

 

 

 

     NSTimer  * timer  =  [ NSTimer  scheduledTimerWithTimeInterval: 0.5

 

                               target: self  selector: @selector ( timerFireMethod: )

 

                               userInfo: [ self  userInfo ]  repeats: YES ];

 

     self . repeatingTimer  =  timer ;

 

}

 

-  ( IBAction ) stopRepeatingTimer: sender  {

 

     [ repeatingTimer  invalidate ];

 

     self . repeatingTimer  =  nil ;

 

}

view raw gistfile1.m This Gist brought to you by  GitHub.

 

1. Unscheduled Timers & Using Invocation

 

// declare

@property (retain) NSTimer *unregisteredTimer;

 

 

 

// implements

- (IBAction)createUnregisteredTimer:sender {

 

    NSMethodSignature *methodSignature = [self methodSignatureForSelector:@selector(invocationMethod:)];

 

    NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:methodSignature];

 

    [invocation setTarget:self];

 

    [invocation setSelector:@selector(invocationMethod:)];

 

    NSDate *startDate = [NSDate date];

 

    [invocation setArgument:&startDate atIndex:2];

 

 

    NSTimer *timer = [NSTimer timerWithTimeInterval:0.5 invocation:invocation repeats:YES];

 

    self.unregisteredTimer = timer;

 

}

 

 

 

- (IBAction)startUnregisteredTimer:sender {

 

    if (unregisteredTimer != nil) {

 

        NSRunLoop *runLoop = [NSRunLoop currentRunLoop];

 

        [runLoop addTimer:unregisteredTimer forMode:NSDefaultRunLoopMode];

 

    }

 

}

 

- (IBAction)stopUnregisteredTimer:sender {

 

    [unregisteredTimer invalidate];

 

    self.unregisteredTimer = nil;

 

}