iOS中定时器NSTimer的使用

1、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，需要手动addTimer:forMode: 将timer添加到一个runloop中。

　　而scheduled的初始化方法将以默认mode直接添加到当前的runloop中.

举例：

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];

2、触发（启动）

当定时器创建完（不用scheduled的，添加到runloop中后，该定时器将在初始化时指定的timeInterval秒后自动触发。

可以使用-(void)fire;方法来立即触发该定时器；

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.

在重复执行的定时器中调用此方法后立即触发该定时器，但不会中断其之前的执行计划；

在不重复执行的定时器中调用此方法，立即触发后，就会使这个定时器失效。

3、停止

- (void)invalidate;

这个是唯一一个可以将计时器从runloop中移出的方法。

注：

NSTimer可以精确到50-100毫秒.

NSTimer不是绝对准确的,而且中间耗时或阻塞错过下一个点,那么下一个点就pass过去了.

延时函数和Timer的使用

//延时函数： [NSThread sleepForTimeInterval:5.0]； //暂停5s. //Timer的使用： NSTimer *connectionTimer; //timer对象 //实例化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作为延时的一种方法  do{
[[NSRunLoopcurrentRunLoop]runUntilDate:[NSDatedateWithTimeIntervalSinceNow:1.0]];
}while(!done); //timer调用函数 -(void)timerFired:(NSTimer *)timer{
done =YES;
}

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

创建 NSTimer

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，如果没有重复执行的timer相当于

[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.

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; }

秒客网

iOS中定时器NSTimer的使用

iOS中定时器NSTimer的使用

创建 NSTimer

相关文章