ios – 方法Swizzling不起作用

class Swizzle: NSObject
{
    dynamic func method()
    {
        print("A")
    }
}

修改声明,它应该工作.@H_404_3@

在Swift中使用方法调配时,您的类/方法必须符合以下两个要求：@H_404_3@

>您的课程必须扩展NSObject
>您想要调配的函数必须具有动态属性@H_404_3@

有关为何需要此操作的完整说明,请查看Using Swift with Cocoa and Objective-C：@H_404_3@

Swift 3更新：@H_404_3@

关于GCD已经有一些变化,并且dispatch_once不再可用.为了执行相同的一次操作,我们可以将代码包含在全局静态类常量的初始化块中.@H_404_3@

Swift语言保证此代码在应用程序的生命周期内仅执行一次.@H_404_3@

class TestSwizzling : NSObject {
    dynamic func methodOne()->Int{
        return 1
    }
}

extension TestSwizzling {

    //In Objective-C you'd perform the swizzling in load(),//but this method is not permitted in Swift
    override class func initialize()
    {

        struct Inner {
            static let i: () = {

                let originalSELEctor = #SELEctor(TestSwizzling.methodOnE)
                let swizzledSELEctor = #SELEctor(TestSwizzling.methodTwo)                 
                let originalMethod = class_geTinstanceMethod(TestSwizzling.self,originalSELEctor);
                let swizzledMethod = class_geTinstanceMethod(TestSwizzling.self,swizzledSELEctor)                
                method_exchangeImplementations(originalMethod,swizzledMethod)
            }
        }
        let _ = Inner.i
    }

    func methodTwo()->Int{
        // It will not be a recursive call anymore after the swizzling
        return methodTwo()+1
    }
}

var c = TestSwizzling()
print(c.methodOne())
print(c.methodTwo())

Swift 2.2更新：@H_404_3@

我已经为新的#SELEctor属性更新了原始示例：@H_404_3@

class TestSwizzling : NSObject {
    dynamic func methodOne()->Int{
        return 1
    }
}

extension TestSwizzling {

    //In Objective-C you'd perform the swizzling in load(),//but this method is not permitted in Swift
    override class func initialize()
    {
        struct Static
        {
            static var token: dispatch_once_t = 0
        }

        // Perform this one time only
        dispatch_once(&Static.token)
        {
                let originalSELEctor = #SELEctor(TestSwizzling.methodOnE)
                let swizzledSELEctor = #SELEctor(TestSwizzling.methodTwo)                 
                let originalMethod = class_geTinstanceMethod(self,originalSELEctor);
                let swizzledMethod = class_geTinstanceMethod(self,swizzledMethod)
        }
    }

    func methodTwo()->Int{
        // It will not be a recursive call anymore after the swizzling
        return methodTwo()+1
    }
}

var c = TestSwizzling()
print(c.methodOne())
print(c.methodTwo())

如果您需要一个示例,请查看此示例项目on github.@H_404_3@