mutating method sent to immutable object

-[__NSCFDictionary setObject:forKey:]: mutating method sent to immutable object' 解决方法：

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

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

数组相似：  

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

objectForKey:@"userArray"] ];

总结，从NSUserDefaults取出数据时注意用这两个方法。