UIImageView之userInteractionEnabled 属性

       我们往往喜欢用UIImageView最为我们程序的背景，然后再在其上面添加其他的控件。如果直接拖到控件到UImageView上面，可以发现控件并不是属于UIImageView，而是与其并列属于UIView的。但是用代码加的话发现可以用addSubView:方法给它上面加控件，但是程序运行起来就会发现UIImageView上面的控件（比如UIButton、UITextField）根本无法响应事件。这就要用到它的userInteractionEnabled 属性。

     苹果帮助文档是这样解释的：

New image view objects are configured to disregard user events by default.

If you want to handle events in a custom subclass of UIImageView, you must explicitly change the value of the userInteractionEnabled property to YES after initializing the object.

userInteractionEnabled

A Boolean value that determines whether user events are ignored and removed from the event queue.

@property(nonatomic, getter=isUserInteractionEnabled) BOOL userInteractionEnabled

Discussion

This property is inherited from the UIView parent class. This class changes the default value of this property to NO.

Availability

• Available in iOS 2.0 and later.

Declared In

UIImageView.h

这就说明UIImageView默认是忽略事件的，不会响应事件的（用代码添加，会发现这个效果）。只有修改它的这个属性为YES它上面的控件才可以响应事件。也可以将其他控件直接加到VIew上面与UIImageView并列。