NSMutableArray *list =[NSMutableArray array];
[list addObject:@"1"];
[list addObject:@"2"];
[list addObject:@"3"];
[list addObject:@"4"];
//copy 出 新数组 不可变
NSArray *copy_list =[list copy];
//copy 出 新数组 可变
NSMutableArray *mut_list =[list mutableCopy];
//指针区别
NSLog(@"points : %p %p %p ",list,copy_list,mut_list);
// 返回同一数组
NSArray *copy_list2=[copy_list copy];
// copy出可变 新数组
NSMutableArray *mut_list2=[copy_list mutableCopy];
NSLog(@"points : %p %p ", copy_list,copy_list2);
参考: 1[http://stackoverflow.com/questions/2002174/copy-mutablecopy]