IOS触摸跟踪代码 [英] IOS touch tracking code

问题描述

我正在 Xcode 中为 iPhone 制作一个应用程序，它需要一个框来仅在 X 轴上跟随我的手指.我在网上找不到任何解决方案，而且我的编码知识也不是很好.

I'm making an app for iPhone in Xcode, and It requires a box to follow my finger only on the X axis. I couldn't find any solution online to this, and my coding knowledge isn't that great.

我一直在尝试使用 touchesBegan 和 touchesMoved.

I've been trying to use touchesBegan and touchesMoved.

有人可以帮我写一些代码吗?

Could someone please write me up some code please?

推荐答案

首先你需要 UIGestureRecognizerDelegate 在你的 ViewController.h 文件中:

First you need the UIGestureRecognizerDelegate on your ViewController.h file:

@interface ViewController : UIViewController <UIGestureRecognizerDelegate>

@end

然后在 ViewController.m 上声明一个 UIImageView，就像这样，使用 BOOL 来跟踪内部是否发生触摸事件你的 UIImageView:

Then you declare an UIImageView on your ViewController.m, like so, with a BOOL to track if a touch event is occurring inside your UIImageView:

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

然后在viewDidLoad上初始化UIImageView:

- (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，您可以开始使用这些方法对最适合您的内容进行修改:

After that you can start doing your modifications to what's best for you using these methods:

-(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...");
    }

} 

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