触摸事件About Events in iOS

3触摸事件About Events in iOS

1、UIKit Makes It Easy for Your App to Detect Gestures

uicontrol、Gesture recognizers（powerful, reusable, and adaptable.）

create your own gesture recognizer to recognize a new gesture

2、An Event Travels Along a Specific Path Looking for an Object to Handle It

事件响应链

UIEvent：封装一系列的触摸事件

对于 motion events，取决于你所使用的framework以及type

the hit-test view:-------the event to the view where the touch occurred.

The lowest view in the view hierarchy that contains the touch point becomes the hit-test view

Motion and remote control events——send to the first responder for handling

hit-test检查order：从super  到sub

so, 超出super的subview的部分，响应不到(super并不包含sub超出super的frame)

A touch object is associated with its hit-test view for its lifetime, even if the touch later moves outside the view.

An object becomes the first responder by doing two things:

1--- Overriding the canBecomeFirstResponder method to return YES.

2-----Receiving a becomeFirstResponder message. If necessary, an object can send itself this message.

If you try to assign the first responder in viewWillAppear:, your object graph is not yet established, so the becomeFirstResponder method returns NO.

Text editing. When a user taps a text field or a text view, that view automatically becomes the first responder. By default, the virtual keyboard appears and the text field or text view becomes the focus of editing. You can display a custom input view instead of the keyboard if it’s appropriate for your app. You can also add a custom input view to any responder object.