使用NSMutableDictionary時扒秸，如果操作不當，有可能會引起程序崩潰嗽元。示例代碼：
NSString *result = @"{\"username\”:\”aaa\”,\"phone\":\"15666666666\",\"bankcount\":\"98765432112345678\"}";
NSData *data = [result dataUsingEncoding:NSUTF8StringEncoding];
NSMutableDictionary *info = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableLeaves error:nil];
if (info) {
NSString *username = [Utils UrlDecode: info[@"username"]];
[info setObject:username forKey:@"username"];
}
執(zhí)行上述代碼后報錯：
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '-[__NSCFDictionary setObject:forKey:]: mutating method sent to immutable object'
出錯原因在于：
[NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableLeaves error:nil];
返回的結果是immutable對象阴孟，不能直接對immutable進行賦值操作，否則會報錯昼榛。
修改后代碼：
NSString *result = @"{\"username\”:\”aaa\”,\"phone\":\"15666666666\",\"bankcount\":\"98765432112345678\"}";
NSData *data = [result dataUsingEncoding:NSUTF8StringEncoding];
//－－－－將immutable轉換為mutable－－－－
NSMutableDictionary *temp = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableLeaves error:nil];
NSMutableDictionary *info = [NSMutableDictionary dictionaryWithDictionary:temp];
//－－－－－－－－－－－－－－－－－－－－－－
if (info) {
NSString *username = [Utils UrlDecode:info[@"username"]];
[info setObject:username forKey:@"username"];
}
NSMutableDictionary *dic = [getDefaults valueForKey:@"loginInfo"];
[dic2 setObject:tf1.text forKey:@"phone"];
報錯:
'-[__NSCFDictionary setObject:forKey:]: mutating method sent to immutable object
修改:
NSMutableDictionary *dic = (NSMutableDictionary *)[getDefaults valueForKey:@"loginInfo"];
NSMutableDictionary *dic2 = [NSMutableDictionary dictionaryWithDictionary:dic];
[dic2 setObject:tf1.text forKey:@"phone"];
