ios - KVO 不工作 : message was received but not handled

Question

我在使用 KVO 时遇到以下错误。它只适用于 UIViewController 的子类吗？

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")

Answer 1

根据docs ，该方法的名称是 observeValue(forKeyPath:of:change:context:)。请注意 of:，而不是您所使用的 ofObject:。您的方法不是所需方法的实现。我相信您需要使用 override 标记正确命名的方法(事实上，编译器会让您在没有该方法的情况下逃脱，这表明您的名称错误)。