December 2016
Intermediate to advanced
416 pages
15h 21m
English
Content preview from iOS Programming: The Big Nerd Ranch Guide, 6th Edition
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18 Touch Events and UIResponder
In the next two chapters, you will create TouchTracker, an app that lets the user draw by touching the screen. In this chapter, you will create a view that draws lines in response to the user dragging across it (Figure 18.1). Using multitouch, the user will be able to draw more than one line at a time.
Figure 18.1 TouchTracker
Touch Events
As a subclass of UIResponder, a UIView can override four methods to handle the four distinct touch events:
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one or more fingers touch the screen
func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?)
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one or more fingers ...
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