SwiftUI 装饰器 @State_swiftui @state wrappedvalue

import UIKit
 
 
/**
 * 模仿SwiftUI @State注解
 *
**/
 
@propertyWrapper
struct AState<T> {
    // class 是引用，不存在值拷贝的情况
    private var bind: B
    
    init(wrappedValue : T) {
        bind = B(wrappedValue)
    }
    
    var wrappedValue : T {
        get {
            self.bind.val
        }
        
        nonmutating set {
            self.bind.val = newValue
        }
    }
    
    class B {
        var val : T
        init(_ wrappedValue: T) {
            self.val = wrappedValue
        }
    }
}
 
 
struct CT {
    @AState var val:String
}
 
 
// 测试输出
 
var ct = CT(val: "222")
var ct2 = ct
 
ct.val = "111"
print("ct >> \(ct.val)")
print("ct2 >> \(ct2.val)")