'NSInvalidArgumentException'，原因：'*** setObjectForKey：对象不能为 nil（键：device_uid）'

Question

尝试在 iPhone 上运行应用程序时出现错误。我不明白为什么在这种情况下我有一个 nil 错误

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '  setObjectForKey: object cannot be nil (key: device_id)'
First throw call stack: (0x183ce0f48 0x19918bf80 0x183bcc4e0 0x10006f5f0 0x1002b9ca8 0x1002b9c68 0x1002bf710 0x183c981f8 0x183c96060 0x183bc4ca0 0x18f148088 0x1892dcffc 0x1000716a0 0x1999ce8b8)
libc++abi.dylib: terminating with uncaught exception of type NSException

这是 appdelegate.m 文件中与此错误有关的部分：

// Get the users Device Model, Display Name, Token & Version Number
UIDevice *device = [UIDevice currentDevice];

NSUserDefaults *dict = [NSUserDefaults standardUserDefaults];
NSString *identifier = [dict stringForKey:@"identifier"];
NSString *deviceName = device.name;
NSString *deviceModel = device.model;
NSString *deviceSystemVersion = device.systemVersion;

// Prepare the Device Token for Registration (remove spaces and < >)
NSString *deviceToken = [[[[token description]
stringByReplacingOccurrencesOfString:@"<"withString:@""]
stringByReplacingOccurrencesOfString:@">" withString:@""]
stringByReplacingOccurrencesOfString: @" " withString: @""];

NSMutableDictionary *postDatas = [NSMutableDictionary dictionary];
[postDatas setObject:appName forKey:@"app_name"];
[postDatas setObject:appVersion forKey:@"app_version"];
[postDatas setObject:identifier forKey:@"device_uid"];
[postDatas setObject:deviceToken forKey:@"device_token"];
[postDatas setObject:deviceName forKey:@"device_name"];
[postDatas setObject:deviceModel forKey:@"device_model"];
[postDatas setObject:deviceSystemVersion forKey:@"device_version"];
[postDatas setObject:pushBadge forKey:@"push_badge"];
[postDatas setObject:pushAlert forKey:@"push_alert"];
[postDatas setObject:pushSound forKey:@"push_sound"];

Request *request = [Request alloc];
request.delegate = self;

[request postDatas:postDatas withUrl:@"push/iphone/registerdevice/"];

此方法是否已弃用？

Answer 1

标识符中的值为零。所以请像这样检查它

NSString *identifier = [dict stringForKey:@"identifier"];

if([identifier length] != 0)
    [postDatas setObject:identifier forKey:@"device_uid"];
else
    [postDatas setObject:@"" forKey:@"device_uid"];

Answer 2

您不能将 nil 值放入字典中。它会崩溃。

您真正需要调查的内容是：这些 nil 值从何而来，当您获得 nil 值时应该做什么？那是只有你可以决定的事情。 Mukesh 的回答应该你如何存储一个空字符串而不是 nil。这样可以避免崩溃。 通常是正确的做法，但并非总是如此。因此，如果其中一个值为 nil，请调查您的应用程序应该做什么，并使其完全做到这一点。