ios - NSTimer 发射超过它应该的

Question

我知道这是我的问题而不是 NSTimer 的问题，但如果有人能帮助我，我将不胜感激。在我的项目中，我需要每 0.5 秒为 2 个对象调用此方法。问题是计时器在不同的时间触发。它可能会立即触发 3 或 5 次(两个对象一起触发)，然后它会在 0.5 秒后重复执行相同的操作。

-(void) blinkLamp{
switch (currentState) {
    case blinkingGreen:
        NSLog(@"blink green lamp");
        self.greenLamp = !self.greenLamp;
        self.colorState[0] = [NSNumber numberWithBool:greenLamp];
        self.rndValuesChanged = rand();
        break;
    case blinkingYellow:
        NSLog(@"blink yellow lamp");
        self.yellowLamp = !self.yellowLamp;
        self.colorState[1] = [NSNumber numberWithBool:yellowLamp];
        self.rndValuesChanged = rand();
        break;
    default:
        break;
}
[NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:@selector(blinkLamp) userInfo:nil repeats:NO];
}

此方法在 SetState 方法中调用一次。

-(void) setState:(State)newState{
currentState = newState;
switch (newState) {
    case green:
        self.greenLamp = YES;
        self.yellowLamp = NO;
        self.redLamp = NO;
        break;
    case yellow:
        self.greenLamp = NO;
        self.yellowLamp = YES;
        self.redLamp = NO;
        break;
    case red:
        self.greenLamp = NO;
        self.yellowLamp = NO;
        self.redLamp = YES;
        break;
    case redYellow:
        self.greenLamp = NO;
        self.yellowLamp = YES;
        self.redLamp = YES;
        break;
    case off:
        self.greenLamp = NO;
        self.yellowLamp = NO;
        self.redLamp = NO;
        break;
    case blinkingGreen:
        self.greenLamp = YES;
        self.yellowLamp = NO;
        self.redLamp = NO;
        [NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:@selector(blinkLamp) userInfo:nil repeats:NO];
        break;
    case blinkingYellow:{
        self.greenLamp = NO;
        self.yellowLamp = YES;
        self.redLamp = NO;
        [NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:@selector(blinkLamp) userInfo:nil repeats:NO];
        //[self blinkLamp];

        break;}
    default:
        NSLog(@"This mode is not allowed for VehicleTL");
    break;}
NSLog(@"G - %d Y - %d R - %d", self.greenLamp, self.yellowLamp, self.redLamp);
self.colorState[0] = [NSNumber numberWithBool:greenLamp];
self.colorState[1] = [NSNumber numberWithBool:yellowLamp];
self.colorState[2] = [NSNumber numberWithBool:redLamp];
self.rndValuesChanged = rand();

Answer 1

您没有跟踪现有计时器，而是创建了多个计时器，这就是您让它们多次触发的原因。

使用实例变量，并且只在当前无效时创建一个计时器:

case blinkingGreen:
    self.greenLamp = YES;
    self.yellowLamp = NO;
    self.redLamp = NO;
    [self createBlinkingTimer];
    break;
case blinkingYellow:{
    self.greenLamp = NO;
    self.yellowLamp = YES;
    self.redLamp = NO;
    [self createBlinkingTimer];
    //[self blinkLamp];

...

- (void)createBlinkingTimer
{
    if (!self.blinkingTimer.isValid) 
        self.blinkingTimer = [NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:@selector(blinkLamp) userInfo:nil repeats:NO];
}