检查 NSTimer 是否被添加到 NSRunLoop

Checking if NSTimer was added to NSRunLoop

假设我在代码中的某个地方创建了 NSTimer,稍后我想将它添加到 mainRunLoop 中,前提是之前还没有添加它:

NSTimer* myTimer = [NSTimer timerWithTimeInterval:1.0f
                                                target:self
                                                selector:@selector(targetMethod:)
                                                userInfo:nil
                                                repeats:YES];

代码中的另一个地方:

if("my myTimer wasn't added to the mainRunLoop")
{
    NSRunLoop *runLoop = [NSRunLoop mainRunLoop];
    [runLoop addTimer:myTimer forMode:NSDefaultRunLoopMode];
}

有没有办法检查这个?

是;在实例变量中保留对它的引用并检查非 nil:

@interface MyClass() {
    NSTimer *_myTimer;
}
@end

...

if (!_myTimer)
{
    _myTimer = [NSTimer timerWithTimeInterval:1.0f
                                       target:self
                                     selector:@selector(targetMethod:)
                                     userInfo:nil
                                      repeats:YES];
    NSRunLoop *runLoop = [NSRunLoop mainRunLoop];
    [runLoop addTimer:_myTimer forMode:NSDefaultRunLoopMode];
}

试试这个:

CFRunLoopRef loopRef = [[NSRunLoop mainRunLoop] getCFRunLoop];
BOOL timerAdded = CFRunLoopContainsTimer(loopRef, (CFRunLoopTimerRef)myTimer ,kCFRunLoopDefaultMode);

然后检查 timerAdded 变量