如何在Objective-C中取消安排NSTimer的时间

问题描述

我在应用程序中使用嵌套的NSTimer.我这里有两个问题.

I am using nested NSTimer in an application. I have two issues here.

1. 如何在此函数中重新启动时间计数器-(void)updateLeftTime:(NSTimer *)theTimer
2. 如何终止以前的计时器，因为-(void)updateLevel:(NSTimer *)theTimer 也由计时器调用.

1. How to re-initiate time counter in this function - (void)updateLeftTime:(NSTimer *)theTimer
2. How to kill previous timer because - (void)updateLevel:(NSTimer *)theTimer is also calling by timer.

---

- (void)viewDidLoad {
    [super viewDidLoad];

    tmLevel=[NSTimer scheduledTimerWithTimeInterval:20.0f target:self selector:@selector(updateLevel:) userInfo:nil repeats:YES];

    tmLeftTime=[NSTimer scheduledTimerWithTimeInterval:1.0f target:self selector:@selector(updateLeftTime:) userInfo:nil repeats:YES];
}

- (void)updateLevel:(NSTimer *)theTimer {
    static int count = 1;
    count += 1;

    lblLevel.text = [NSString stringWithFormat:@"%d", count];

    tfLeftTime.text=[NSString stringWithFormat:@"%d",ANSWER_TIME];

    tmLeftTime=[[NSTimer alloc] init];
    tmLeftTime=[NSTimer scheduledTimerWithTimeInterval:1.0f target:self selector:@selector(updateLeftTime:) userInfo:nil repeats:YES];
    [self playMusic];

}
- (void)updateLeftTime:(NSTimer *)theTimer {
    static int timeCounter=1;
    timeCounter+=1;
    tfLeftTime.text=[NSString stringWithFormat:@"%d", (ANSWER_TIME-timeCounter)];
}

推荐答案

• 使用 [tmLevel invalidate] 取消计时器的时间表.
• 不要忘记在之后立即设置 tmLevel = nil (以避免在Runloop取消计划并释放计时器后使用变量)
• 在丢失对tmLevel的引用之前，不要忘记使它失效，即在为tmLevel变量分配新的NSTimer之前也调用 [tmLevel invalidate] (否则先前的计时器将继续运行)在新版本的基础上运行)
• Use [tmLevel invalidate] to cancel schedule of a timer.
• Don't forget to set tmLevel=nil immediately after (to avoid using the variable after the timer has been unscheduled and released by the Runloop)
• Don't forget to invalidate the tmLevel timer before loosing the reference to it, namely call [tmLevel invalidate] also before assigning a new NSTimer to the tmLevel variable (or else the previous timer will continue to run in addition to the new one)

还请注意，在您的代码中，您有无用的分配，而且还会造成泄漏:

Note also that in your code you have useless allocations that are moreover creating a leak:

tmLeftTime=[[NSTimer alloc] init];
tmLeftTime=[NSTimer scheduledTimerWithTimeInterval:1.0f target:self selector:@selector(updateLeftTime:) userInfo:nil repeats:YES];

在这里分配一个NSTimer实例，将该实例存储在 tmLeftTime ...中，然后立即忽略此已创建实例，将其替换为使用 [NSTimercheduledTimerWithTimeInterval:]创建的另一个实例...] ！因此，使用 [[[NSTimer alloc] init] 创建的NSTimer丢失了，并且正在造成泄漏(因为它将永远不会被释放).

here you allocate an NSTimer instance, store this instance in tmLeftTime... and then immediately forget about this created instance to replace it with another one, created using [NSTimer scheduledTimerWithTimeInterval:...]!Therefore, the NSTimer created using [[NSTimer alloc] init] is lost, and is creating a leak (as it will never be released).

您的第一行完全没用，就像您在做

Your first line is totally useless, it's kinda like you were doing

int x = 5;
x = 12; // of course the value "5" is lost, replaced by the new value

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