如何在objective-c中按照您的手指制作图像？ [英] How do you make an image follow your finger in objective-c?

问题描述

如何在objetive-c中按照您的手指制作图像？

How do you make an image follow your finger in objetive-c?

推荐答案

• 创建你的 UIView 并配置它（或其任何子类，如 UIImageView ）


• 将图片的位置设置为用户触摸的位置：


• Create your UIView and configure it (or any subclass thereof such as a UIImageView)
• Set the position of your Image to be where the user is touching:

有四个委托方法用于接受触摸事件，这些方法是从 UIResponder ，例如 UIView 。使用最适合您的委托方法。如果你想要它跟随你的手指，这将是 -touchesMoved ：

There are four delegate methods for accepting touch events which are a part of any class that inherits from UIResponder such as a UIView. Use the delegate method that is most appropriate to you. If you want it to follow your finger, this will be -touchesMoved:

- (void) touchesMoved:(NSSet*)toucheswithEvent:(UIEvent*)event {        
    CGPoint pt = [[touches anyObject] locationInView:self];
    myImageView.center = pt;
}

您可以使用的其他委托方法：

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event

我写了一个示例应用程序，它可以完全满足您的需求。这是一个绘制石英2D图形的演示，但它会绘制一个红色正方形和黑色圆圈，您可以拖动手指，并且应该足够简单：

I wrote an example application that does exactly what you want. It's a demo of drawing Quartz 2D graphics, but it draws a red square and black circle where you drag your finger and should be simple enough to follow:

替代文字http://brockwoolf.com/shares/stackoverflow/3445494/screen.png

下载Xcode项目（ 32kb）

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