IOS触摸跟踪代码

Question

我正在Xcode中为iPhone制作应用程序，并且它只需要一个框，以便仅在X轴上跟随我的手指。我无法在网上找到任何解决方案，而且我的编码知识也不是很好。

我一直在尝试使用touchesBegan和touchesMoved。

请问有人可以给我写一些代码吗？

Answer 1

首先你需要的UIGestureRecognizerDelegate您ViewController.h文件：

@interface ViewController : UIViewController <UIGestureRecognizerDelegate> 

@end 

然后你申报你的ViewController.m一个UIImageView，像这样，有BOOL跟踪，如果触摸事件UIImageView：

@interface ViewController() { 
    UIImageView *ballImage; 
    BOOL touchStarted; 
} 

然后你初始化UIImageView上viewDidLoad：

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    UIImage *image = [UIImage imageNamed:@"ball.png"]; 
    ballImage = [[UIImageView alloc]initWithImage:image]; 
    [ballImage setFrame:CGRectMake(self.view.center.x, self.view.center.y, ballImage.frame.size.width, ballImage.frame.size.height)]; 
    [self.view addSubview:ballImage]; 
} 

之后，你可以开始做你的修改，什么是最好的，你使用这些方法：

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 
{ 
    UITouch *touch = [touches anyObject]; 
    CGPoint touch_point = [touch locationInView:ballImage]; 

    if ([ballImage pointInside:touch_point withEvent:event]) 
    { 
     touchStarted = YES; 

    } else { 

     touchStarted = NO; 
    } 
} 

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event 
{ 
    if ([touches count]==1 && touchStarted) { 
     UITouch *touch = [touches anyObject]; 
     CGPoint p0 = [touch previousLocationInView:ballImage]; 
     CGPoint p1 = [touch locationInView:ballImage]; 
     CGPoint center = ballImage.center; 
     center.x += p1.x - p0.x; 
     // if you need to move only on the x axis 
     // comment the following line: 
     center.y += p1.y - p0.y; 
     ballImage.center = center; 
     NSLog(@"moving UIImageView..."); 
    } 

}