mutating method sent to immutable object

-[__NSCFDictionary setObject:forKey:]: mutating method sent to immutable object' 解決方法：

錯誤：NSMutableDictionary*d =[[[NSUserDefaults standardUserDefaults] objectForKey:@"xxxx"] mutableCopy];

修改：NSMutableDictionary*d =[NSMutableDictionary dictionaryWithDictionary:[[NSUserDefaults standardUserDefaults] ForKey:@"xxxx"]];

數組相似：  

NSMutableArray * userArray = [NSMutableArray arrayWithArray:  [ [NSUserDefaults standardUserDefaults]

objectForKey:@"userArray"] ];

總結，從NSUserDefaults取出數據時注意用這兩個方法。