如何启动和关闭计时器？

Question

So i am trying to create a fixed movement for an image, but i can't seem to make it work correctly. The first block is activate by a timer but I don't know how to turn it off and activate another timer to continue the curve.

    BMR = [NSTimer scheduledTimerWithTimeInterval:0.01 target:self selector:@selector(BallArchR) userInfo:nil repeats:YES];
    LMR = [NSTimer scheduledTimerWithTimeInterval:0.01 target:self selector:@selector(BallArchL) userInfo:nil repeats:YES];


    -(void)BallArchR{
        if (Ball.center.x < 284){
            Ball.center = CGPointMake(Ball.center.x + 2.72 , Ball.center.y - 2 );
        }
        if (Ball.center.x >= 284 && Ball.center.x < 488) {
    Ball.center = CGPointMake(Ball.center.x + 2.72 , Ball.center.y + 2 );
        }
    }

    -(void)BallArchL{
        if (Ball.center.x > 284){
            Ball.center = CGPointMake(Ball.center.x - 50 , Ball.center.y - 50 );
        }
        if (Ball.center.x <= 284 && Ball.center.x > 80) {
            Ball.center = CGPointMake(Ball.center.x - 2.72 , Ball.center.y + 2 );
        }
    }

This is the code to make the ball move in a curve, and BallArchR is activated when the game starts up. But i can't turn it off and activate BallArchL. Is there another way to make this work?

Answer 1

- (void)stopTimer 
{
    if ([_LMR isValid]) 
{
        [_LMR invalidate];
    }
}

You can use this for stop timer.

Also for animation you can use

[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:duration];
[UIView setAnimationCurve:UIViewAnimationCurveLinear];
//move your view
[UIView commitAnimations];

or

[UIView animateWithDuration:duration
                            animations:^{
                            //move your view
                            }
];

Answer 2

i think one timer is enough for this

 BMR = [NSTimer scheduledTimerWithTimeInterval:0.01 target:self selector:@selector(BallArchR) userInfo:nil repeats:YES];

-(void)BallArchR
 {
        if (Ball.center.x < 284)
        {
            Ball.center = CGPointMake(Ball.center.x + 2.72 , Ball.center.y - 2 );
        }
        if (Ball.center.x >= 284 && Ball.center.x < 488) 
        {
            Ball.center = CGPointMake(Ball.center.x + 2.72 , Ball.center.y + 2 );
        }
        else
        {
             [self BallArchL ];
        }
  }
  -(void)BallArchL
  {
        if (Ball.center.x > 284)
        {
            Ball.center = CGPointMake(Ball.center.x - 50 , Ball.center.y - 50 );
        }
        if (Ball.center.x <= 284 && Ball.center.x > 80)
        {
            Ball.center = CGPointMake(Ball.center.x - 2.72 , Ball.center.y + 2 );
        }
        else
        {
            [BMR invalidate];
        }
  }

i'm answered this based on what i have understand,if it not what you want comment here your requirement clearly...;)

Answer 3

When you need to deactivate timer, first check if the timer is valid or not then deactivate by using "invalidate" method.

 if ([BMR isValid]) 
{
    [BMR invalidate];
}