How to simplify the lengthy class instance initialization code in the standard library in Swift

Some children's shoes may not be known, and the abbreviated point symbol in Swift is valid for any static member of any type.

Let's actually write an example to look at:

import UIKitclass CFoo{    staticlet sharedInstance = CFoo()}struct SFoo{    staticlet sharedInstance = SFoo()}let foo:CFoo = .sharedInstancelet f:SFoo = .sharedInstance

As you can see in the code above, the Foo type is Cfoo, and cfoo happens to have a static property sharedinstance, so you can use the abbreviated point notation to complete the simplification. The f variable is similar to Foo.

It seems like just a little gimmick, no practical use, but not necessarily, in swift to deal with the traditional OBJC code, you can often see the C-style enumeration initialization code:

animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)

Isn't it annoying? We can write an extension to simplify the syntax (here's the Code excerpt):

extension CAMediaTimingFunction{    // 这个属性会在第一次被访问时初始化。    // (需要添加 @nonobjc 来防止编译器    //  给 static（或者 final）属性生成动态存取器。)    staticlet EaseInEaseOut = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)    // 另外一个选择就是使用计算属性, 它同样很有效,    // 但 *每次* 被访问时都会重新求值：    staticvar EaseInEaseOut: CAMediaTimingFunction {        // .init 是 self.init 的简写        return .init(name: kCAMediaTimingFunctionEaseInEaseOut)    }}

Then we can use it gracefully:

animation.timingFunction.EaseInEaseOut

How to simplify the lengthy class instance initialization code in the standard library in Swift