使用 Objective-C 选择器声明方法时出错

Question

我在尝试声明方法时遇到此错误：

代码如下：

NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("itemDroppedOnCharacter:"), name: "onTargetDropped", object: nil)

func itemDroppedOnCharacter(notif: AnyObject) {

    print("Item Dropped On Character")

}

我做错了什么？

Answer 1

选择器在 Xcode 7.3 中发生了变化。您需要显式声明属于您的 class:

的选择器

class MyClass {
    func someFunc() {
        NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(MyClass.itemDroppedOnCharacter(_:)), name: "onTargetDropped", object: nil)
    }

    @objc func itemDroppedOnCharacter(notif: AnyObject) {
        print("Item Dropped On Character")
    }
}

如果您不想添加 @objc 以将选择器暴露给 Objective-C:

，您也可以让 MyClass 继承自 NSObject

class MyClass: NSObject {
    func someFunc() {
        NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(MyClass.itemDroppedOnCharacter(_:)), name: "onTargetDropped", object: nil)
    }

    func itemDroppedOnCharacter(notif: AnyObject) {
        print("Item Dropped On Character")
    }
}

使用 Objective-C 选择器声明方法时出错

Error declaring method with Objective-C selector

swift

xcode7.3