Question

我有一个NSTimer，可以持续触发advavanceTimer:方法，在剩下的秒数内更新倒计时UILabel。同时CMMotionManager检测到摇动手势并将UIView对象50px移动到右侧，或者说动画不会持续存在。

问题：已解雇的advavanceTimer:方法将UIView移回原点位置

-(void)startCountdownWithTimeLimit:(double)timeLimit {
    self.counter = timeLimit;

    self.countdownTimer = [NSTimer scheduledTimerWithTimeInterval:1
                                                           target:self
                                                         selector:@selector(advanceTimer:)
                                                         userInfo:nil
                                                          repeats:YES];
}

-(void)advanceTimer:(NSTimer*)timer {
    [self setCounter:(self.counter-1)];
    self.countdownLabel.text = [NSString stringWithFormat:@"Countdown: %@", [NSNumber numberWithInt:self.counter]]; //if removed, everything works fine
    //... 
}

-(void)setupMotionManager{
    self.motionManager = [[CMMotionManager alloc] init];
    self.motionManager.deviceMotionUpdateInterval = 0.1;

    [self.motionManager startDeviceMotionUpdatesToQueue:[NSOperationQueue mainQueue]  withHandler:^(CMDeviceMotion *motion, NSError *error)
     {
         [self motionMethod:motion];
     }];
}

-(void)motionMethod:(CMDeviceMotion *)deviceMotion
{
    CMAcceleration userAcceleration = deviceMotion.userAcceleration;
    if (fabs(userAcceleration.x) > accelerationThreshold
        || fabs(userAcceleration.y) > accelerationThreshold
        || fabs(userAcceleration.z) > accelerationThreshold)
    {

        [UIView animateWithDuration:0.5 delay:0.0 options:UIViewAnimationOptionBeginFromCurrentState | UIViewAnimationOptionAllowUserInteraction animations:^{
            CGRect oldFrame = self.movingView.frame;
            CGRect newFrame = CGRectMake(oldFrame.origin.x+50, oldFrame.origin.y, oldFrame.size.width, oldFrame.size.height);
            self.movingView.frame = newFrame;
        } completion:^(BOOL finished) {
        }];

    }
}

Answer 1

问题是您正在使用自动布局。每次设置标签文本时，自动布局都会执行布局。因此，在那一刻，约束出现并将一切都放回到由这些约束所决定的位置。

解决方案：不要更改（动画）任何内容的框架;更改（动画）其约束。

NSTimer重置UIView动画

1 个答案: