[__NSDictionaryI setObject:forKey:]:发送到实例的无法识别的选择器

Question

我正在尝试将"dateTime"添加到我的字典中,如下所示:

Symptom Ranking: {
    5111ef19253b4a9150000000 = 1;
    5111f029253b4add4e000000 = 1;
    5111f036253b4a123d000001 = 1;
    5111f045253b4a404f000000 = 1;
}

NSLog(@"date selected: %@", [[self.datePicker date] description])

[self.results setObject:[[self.datePicker date] description] forKey:@"dateTime"];

应用程序崩溃,我得到这个:

Symptom Tracker[43134:c07] -[__NSDictionaryI setObject:forKey:]: unrecognized selector sent to instance 0x7603990
2013-02-06 08:15:58.741 Symptom Tracker[43134:c07] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSDictionaryI setObject:forKey:]: unrecognized selector sent to instance 0x7603990'
*** First throw call stack:
(0x171b012 0x1428e7e 0x17a64bd 0x170abbc 0x170a94e 0x521e 0x143c705 0x373920 0x3738b8 0x434671 0x434bcf 0x433d38 0x3a333f 0x3a3552 0x3813aa 0x372cf8 0x2652df9 0x2652ad0 0x1690bf5 0x1690962 0x16c1bb6 0x16c0f44 0x16c0e1b 0x26517e3 0x2651668 0x37065c 0x25dd 0x2505)

Answer 1

你的字典是不可变的 - 它是一个NSDictionary而不是一个NSMutableDictionary.修复它,它会正常工作.

Answer 2

当我意外地声明了copy这样的属性时,我遇到了这个错误:

@property (nonatomic,copy) NSMutableDictionary* downloadHandlers;

当我在我这样做时init:

self.downloadHandlers = [[NSMutableDictionary alloc] init];

我实际上有一本不可变的字典.我copy原本以为调用一个可变对象也会给我一个可变对象,但显然不是.无论如何,删除copy关键字(我从来没有打算在那里)解决了问题.

Answer 3

你需要使用NSMutableDictionary- 堆栈跟踪显示你正在使用__NSDictionaryI,(NSDictionary)是不可变的

Answer 4

作为排名靠前的答案,你需要使用NSMutableDictionary而不是NSDictionary.如果你想使用文字,请使用mutableCopy:

NSMutableDictionary* dict = [@{@"key": @"value"} mutableCopy];

这样您就可以使用重新分配密钥了

dict[@"key"] = @"new-value";

Answer 5

当我们处理Web服务响应时,大多数情况下会出现此问题,因为收到的数据是不可变的.当您尝试更改不可变数据时,应用程序肯定会崩溃.我希望以下代码片段能够提供帮助.

NSMutableDictionary  *headerData;

/*Every time you need to allocate memory to the corresponding MutableDictionary variable*/

headerData =[[NSMutableDictionary alloc ]initWithDictionary:response[@"Header"]];