iOS Tutorial

How To Fix Error Use Of Unresolved Identifier ‘RootViewController’ In Xcode Swift Project

When i develop an iOS project in Xcode, i create a custom class RootViewController in RootViewController.swift file, this class is a sub class of UIViewController. But during the development process, when i use this custom class to create an object in another swift file ( for example SceneDelegate.swift ), i meet an error which said …

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How To Set Application Root View Controller Programmatically In Xcode 11

When using Xcode 11 to create a new iOS project, if you still create the root view controller in AppDelegate class’s – func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool function as usual, you will find there is a compile time error which said Value of type ‘AppDelegate’ has no member ‘window’. And …

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What Is The Difference Between iOS UIView Frame And Bounds

UIKit.UIView class has two property frame and bounds, they all save location and size information of the UIView object, but they are different. The difference is that UIView.frame save the data relative to it’s superview’s coordinate system, and UIView.bounds save the data relative to its own coordinate system. This article will show you an example about …

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