ios 如何启动和停止 NSTimer？
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How Can I Start And Stop NSTimer?
提问by trojanfoe
I develop Stop Watch Application.
In my application, there are Two UIButtons , StartBtnand StopBtn, And also I use NSTimer.
我开发秒表应用程序。在我的应用程序中，有两个 UIButtonsStartBtn和StopBtn，而且我使用NSTimer.
Now, i want to start NSTimerwhen user click on StartBtnand also stop when your click on StopBtn.
现在，我想NSTimer在用户单击时开始，StartBtn并在您单击时停止StopBtn。
I know that NSTimeris stopped by [MyTimerName invalidate];method but I don't know how to start NSTimeragain?
我知道这NSTimer被[MyTimerName invalidate];方法阻止了，但我不知道如何重新开始NSTimer？
回答by trojanfoe
The NSTimerclass is a bit awkward to use; rather than separating the creation/destruction from the start/stop, it's all rolled together. In other words the timer starts as soon as it's created and stops as soon as it's destroyed.
这个NSTimer类使用起来有点尴尬；不是将创建/销毁与开始/停止分开，而是全部滚动在一起。换句话说，计时器在创建后立即启动，并在销毁后立即停止。
You therefore need to use the existenceof the NSTimerobject as a flag to indicate if it's running; something like this:
因此，您需要使用存在的的NSTimer对象作为标志，以表明它是否运行; 像这样：
// Private Methods
@interface MyClass ()
{
NSTimer *_timer;
}
- (void)_timerFired:(NSTimer *)timer;
@end
@implementation MyClass
- (IBAction)startTimer:(id)sender {
if (!_timer) {
_timer = [NSTimer scheduledTimerWithTimeInterval:1.0f
target:self
selector:@selector(_timerFired:)
userInfo:nil
repeats:YES];
}
}
- (IBAction)stopTimer:(id)sender {
if ([_timer isValid]) {
[_timer invalidate];
}
_timer = nil;
}
- (void)_timerFired:(NSTimer *)timer {
NSLog(@"ping");
}
回答by Freddy
You could always use fire to start a NStimer again
你总是可以用火重新启动一个 NStimer
[timer fire];
To stop it:
要停止它：
[timer invalidate];
//remember to set timer to nil after calling invalidate;
timer = nil;
回答by Suresh Varma
You can start the timer through
您可以通过以下方式启动计时器
#define kRefreshTimeInSeconds 1
NSTimer *myTimerName;
.
.
myTimerName = [NSTimer scheduledTimerWithTimeInterval: kRefreshTimeInSeconds
target:self
selector:@selector(handleTimer:)
userInfo:nil
repeats:YES];
Then the delegate function:
然后委托函数：
-(void)handleTimer: (id) sender
{
//Update Values in Label here
}
And to stop Timer
并停止计时器
-(void)stopTimer: (id) sender
{
if(myTimerName)
{
[myTimerName invalidate];
myTimerName = nil;
}
}
