NSTimer

1、初始化

+ (NSTimer *)timerWithTimeInterval:(NSTimeInterval)ti invocation:(NSInvocation *)invocation repeats:(BOOL)yesOrNo;

   eg:NSInvocation * invo = [NSInvocation invocationWithMethodSignature:[[self class] instanceMethodSignatureForSelector:@selector(init)]];

     [invo setTarget:self];

     [invo setSelector:@selector(myLog)];

     NSTimer * timer = [NSTimer timerWithTimeInterval:1 invocation:invo repeats:YES];

     //加入主循环池中

     [[NSRunLoop mainRunLoop]addTimer:timer forMode:NSDefaultRunLoopMode]; 

     //开始循环

     [timer fire];//立即启动

+ (NSTimer *)scheduledTimerWithTimeInterval:(NSTimeInterval)ti invocation:(NSInvocation *)invocation repeats:(BOOL)yesOrNo;

      eg:NSTimer * timer = [NSTimer scheduledTimerWithTimeInterval:1 invocation:invo repeats:YES];

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

      eg:NSTimer * timer = [NSTimer timerWithTimeInterval:1 target:self selector:@selector(myLog) userInfo:nil repeats:NO] ;

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

      eg:NSTimer * timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(myLog:) userInfo:@"123" repeats:YES];

 

- (instancetype)initWithFireDate:(NSDate *)date interval:(NSTimeInterval)ti target:(id)t selector:(SEL)s userInfo:(id)ui repeats:(BOOL)rep 

      eg:NSTimer * timer = [[NSTimer alloc]initWithFireDate:[NSDate distantPast] interval:1 target:self selector:@selector(myLog:) userInfo:nil repeats:YES];

      [[NSRunLoop mainRunLoop]addTimer:timer forMode:NSDefaultRunLoopMode];

 

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.

 

4、- (NSDate *)fireDate;//开始时间

5、- (void)setFireDate:(NSDate *)date;//设置fireData，其实暂停、开始会用到

 [timer setFireDate:[NSDate date]]; //继续。

[timer setFireDate:[NSDate distantPast]];//开启

[timer setFireDate:[NSDate distantFuture]];//暂停

6、- (NSTimeInterval)timeInterval;//延迟时间

 

7、- (void)invalidate;//停止并删除

删除之前最好判断是否还在线程中

if ([scrollTimer isValid] == YES) {

        [scrollTimer invalidate];

        scrollTimer = nil;

}

8、- (BOOL)isValid;//判断是否valid

 

9、- (id)userInfo;//通常用nil