NStimer 在滚动ScrollView的时候停止,在新线程中使用NSTimer

方法一：

-(void) viewDidLoad{
[self performSelectorInBackground:@selector(call1) withObject:nil]; 
}

-(void) call1{
timer1 = [NSTimer scheduledTimerWithTimeInterval:3.0 target:self selector:@selector(doSomething) userInfo:nil repeats:NO];

[[NSRunLoop currentRunLoop] addTimer:timer1 forMode:NSRunLoopCommonModes];

}

-(void) call2{
// do something
timer1 invalidate];
timer1 = nil;
}

方法二：

<code style="padding: 0px; border-width: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline; background-color: rgb(238, 238, 238);"><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">(</span><span style="color: rgb(0, 0, 139); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">void</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">)</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">viewDidAppear</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:(</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">BOOL</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">)</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">animated </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">{</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">    </span><span style="color: rgb(43, 145, 175); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">NSThread</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">*</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> timerThread </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">[[</span><span style="color: rgb(43, 145, 175); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">NSThread</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> alloc</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">]</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> initWithTarget</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span style="color: rgb(0, 0, 139); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">self</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> selector</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span style="color: rgb(128, 0, 0); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">@selector</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">(</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">timerStart</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">)</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> </span><span style="color: rgb(0, 0, 139); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">object</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span style="color: rgb(0, 0, 139); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">nil</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">];</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">    </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">[</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">timerThread start</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">];</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"></span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">}</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"></span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-(</span><span style="color: rgb(0, 0, 139); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">void</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">)</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">timerStart</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">{</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">    </span><span style="color: rgb(43, 145, 175); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">NSAutoreleasePool</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">*</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">pool </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">[[</span><span style="color: rgb(43, 145, 175); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">NSAutoreleasePool</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> alloc</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">]</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> init</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">];</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">    </span><span style="color: rgb(43, 145, 175); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">NSRunLoop</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">*</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> runLoop </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">[</span><span style="color: rgb(43, 145, 175); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">NSRunLoop</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> currentRunLoop</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">];</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">    timer </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">[[</span><span style="color: rgb(43, 145, 175); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">NSTimer</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> scheduledTimerWithTimeInterval</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span style="color: rgb(128, 0, 0); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">1.0</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> target</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span style="color: rgb(0, 0, 139); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">self</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> selector</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span style="color: rgb(128, 0, 0); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">@selector</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">(</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">method</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">)</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> userInfo</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span style="color: rgb(0, 0, 139); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">nil</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> repeats</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">YES</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">]</span><span style="color: rgb(255, 102, 0); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> retain</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">];//一定要retain，不然timerStart执行完后，NSTimer就被释放了。</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">    </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">[</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">runLoop run</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">];</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">    </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">[</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">pool release</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">];</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"></span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">}</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"></span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">(</span><span style="color: rgb(0, 0, 139); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">void</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">)</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">viewDidDisappear</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:(</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">BOOL</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">)</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">animated </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">{</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">    </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">[</span><span style="color: rgb(0, 0, 139); padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">super</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> viewDidDisappear</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">animated</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">];</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">    </span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">[</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">timer invalidate</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">];</span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"></span><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">}</span></code>

<code style="padding: 0px; border-width: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline; background-color: rgb(238, 238, 238);"><span style="padding: 0px; border-width: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">方法三：</span></code>

<span style="font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;">timer = [NSTimer timerWithTimeInterval:5.0 target:self selector:@selector(SendHeartBeat) userInfo:nil repeats:YES];</span>

<span style="font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;"> [[NSRunLoop mainRunLoop] addTimer:heartTimer forMode:NSDefaultRunLoopMode];</span>