为 UIImageView 实现 UITouchDown

Implement UITouchDown for UIImageView(为 UIImageView 实现 UITouchDown)

问题描述

我知道如何为 UIImageView 实现 touchesBegan

I know how to implement touchesBegan for UIImageView

是否可以为 UIImageView 实现 UITouchDown ?(我知道我可以使用 touchesBegan 而不是 UITouchDown 但我想实现 UITouchDown)

is it possible to implement UITouchDown for UIImageView ?(i know that i can use touchesBegan instead of UITouchDown but i want to implement UITouchDown)

推荐答案

使用 UIButton.

UIButton *aButton = [UIButton buttonWithType:UIButtonTypeCustom];
[aButton setImage:someUIImage forState:UIControlStateNormal];
[aButton addTarget:self action:@selector(aMethod) forControlEvents:UIControlEventTouchUpInside];

[self.view addSubview:aButton];

UIButton 的替代品(更长的方法)

UIControl 已经实现了用户交互并支持细粒度的用户交互.您可以结合 UIImageView 和 UIControl 的功能来实现这一点，因为它们都是 UIView 的子类.

A UIControl implements user interactions and support for fine-grained user interactions already. You can combine the functionality of a UIImageView and a UIControl to achieve this since both are subclasses of UIView.

要获得此行为，请将 UIImageView 的对象作为子视图添加到 UIControl 以便完全覆盖图像.然后使用 addTarget:action:forControlEvents:.这是一个例子:

To get this behavior, add an object of UIImageView as a subview to a UIControl such that the image is fully covered. Then add a event handler to this control using addTarget:action:forControlEvents:. Here's an example:

// assuming the image view object exists
UIImageView *anImageView = ..;

// create a mask that the covers the image exactly
UIControl *mask = [[UIControl alloc] initWithFrame:anImageView.frame];

// add the image as a subview of this mask
CGSize imageSize = anImageView.frame.size;
anImageView.frame = CGRectMake(0, 0, imageSize.width, imageSize.height);
[mask addSubview:anImageView];

// add a target-action for the desired control events to this mask
[mask addTarget:self action:@selector(someMethod:) forControlEvents:UIControlEventTouchUpInside];

// add the mask as a subview instead of the image
[self.view addSubview:mask];

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