NSMutableDictionary：发送到不可变对象的变异方法-解网

问：

以下代码返回异常，并显示以下错误消息“mutating method sent to immutable object”时尝试删除 ObjectForKey

NSMutableDictionary * storedIpDictionary = (NSMutableDictionary*)[[NSUserDefaults standardUserDefaults] dictionaryForKey:@"dictDeviceIp"];

NSString *key = self.currentDeviceNameText.text;
NSString *ipAddressTemp = [storedIpDictionary objectForKey:key];

[storedIpDictionary removeObjectForKey:key]; <----Crashes here

storedIpDictionary[key] = ipAddressTemp;

不确定问题是什么，可能是由于从 NSUserDefaults 检索字典。

但是，以下代码可以正常工作，没有任何问题。

NSMutableDictionary * storedIpDictionary = (NSMutableDictionary*)[[NSUserDefaults standardUserDefaults] dictionaryForKey:@"dictDeviceIp"];
[storedIpDictionary removeAllObjects];

iOS的目标-C nsuserdefaults nsmutable词典可变

NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
NSMutableDictionary *storedIpDictionary = [[userDefaults dictionaryForKey:@"dictDeviceIp"] mutableCopy];

NSString *key = self.currentDeviceNameText.text;
NSString *ipAddressTemp = [storedIpDictionary objectForKey:key];

// Don't need this line
//[storedIpDictionary removeObjectForKey:key];

storedIpDictionary[key] = ipAddressTemp;
[userDefaults setObject:storedIpDictionary
                 forKey:@"dictDeviceIp"];

3赞 Remixed123 8/5/2014 #4

这是最终起作用的代码，我使用了上面其他人提供的一些细节，但没有一个完全解释。

- (void)cleanDictionary
{
    NSMutableDictionary * storedIpDictionary = [[[NSUserDefaults standardUserDefaults] objectForKey: @"dictDeviceIp"] mutableCopy];

    [[NSUserDefaults standardUserDefaults] removeObjectForKey:@"dictDeviceIp"];

    NSString *oldKey = self.currentDeviceNameText.text;
    NSString *newKey = self.deviceNameChangeText.text;
    NSString *ipAddressTemp = [storedIpDictionary objectForKey:oldKey];

    // Make some change to the structure
    [storedIpDictionary removeObjectForKey:oldKey];  // Remove object
    storedIpDictionary[newKey] = ipAddressTemp;      // Add object with new key

    // Add it the whole thing back into NSUserDefaults
    [[NSUserDefaults standardUserDefaults] setObject:storedIpDictionary forKey:@"dictDeviceIp"];

    // Synchronize to ensure it's saved
    [[NSUserDefaults standardUserDefaults] synchronize];
}

3赞 Pablo Ruan 10/30/2015 #5

如果您在 Swift 中遇到错误 NSMutableDictionary： mutating method sent to immutable object，请执行以下步骤：

这是因为您已将 NSUserDefault 分配给 NSMutableArray，当您获取某些 NSUserDefault 时，它会返回 NSArray 而不是 NSMutableArray，因此在这种情况下，您必须使用 NSMutableArray Auxiliary 。

请参阅 Swift：

var Products:NSMutableArray = NSMutableArray()


override func viewDidAppear(animated: Bool) {

    if let Produtos = NSUserDefaults.standardUserDefaults().valueForKey("Produtos") {
        Products = Produtos as! NSMutableArray
    }
}

func InsertProducts(productCode:String){
     //COPY Products Atual for auxMutable
     var auxMutable = Products.mutableCopy()

        //Add object in auxMutable
        auxMutable.addObjectsFromArray([productCode])

        //in line back data to Array Products and make cast to NSMutableArray
        Products = auxMutable as! NSMutableArray

        //Refresh Data of NSUserDefaults
        NSUserDefaults.standardUserDefaults().setObject(Products, forKey: "Produtos")
}


@IBAction func Bt_New_Product(sender: AnyObject) {
     var ProductName:String = TXT_NameProduct.text

     InsertProducts(ProductName)
}

这对我有用!!

3赞 AyAz 6/20/2016 #6

我发现了同样的问题并找到了解决方案，希望它能帮助一些人。

arrayOfferId = defaults.objectForKey("offerId")?.mutableCopy() as! NSMutableArray

NSUserDefaults 返回不可变对象，即使放入可变对象也是如此。您必须对返回的值调用 -mutableCopy 才能获取可变集合。因此，当您从 NSUserDefault 获取值时，请使用 mutableCopy（）

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NSMutableDictionary：发送到不可变对象的变异方法

NSMutableDictionary: mutating method sent to immutable object

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