KVO无法正常工作：已收到邮件但未处理 [英] KVO not working: message was received but not handled

问题描述

玩KVO时出现以下错误。它是否仅适用于UIViewController的子类？

I got the following error when playing around with KVO. Does it only work with subclasses of UIViewController?

Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '<sort.object: 0x100a074e0>: An -observeValueForKeyPath:ofObject:change:context: message was received but not handled.
Key path: name
Observed object: <sort.User: 0x100a06bb0>
Change: {
    kind = 1;
    new = Test;
}

代码如下：

import Foundation

class User: NSObject {
    dynamic var name: String?
}

class object: NSObject {
    func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutableRawPointer) {
        print("Name changed")
    }
}


var user = User()
var ob = object()
user.addObserver(ob, forKeyPath: "name", options: NSKeyValueObservingOptions.new, context: nil)

user.name = "Test"

try user.name = "Test 2"
user.removeObserver(ob, forKeyPath: "name")

推荐答案

根据 docs ，方法的名称是 observeValue（forKeyPath：of：change：context：）。注意：，而不是 ofObject：。您的方法不是所需方法的实现。我相信你需要用覆盖来标记正确命名的方法（以及编译器让你逃脱的事实，如果没有这个，就表明你的名字错了）。

According to the docs, the name of the method is observeValue(forKeyPath:of:change:context:). Note of:, not ofObject: as you have. Your method is not an implementation of the required method. I believe you'll need to mark the properly-named method with override (and the fact that the compiler let you get away without that was a sign that you had the name wrong).

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