copy

NSString *str1 = @"abc";
NSString *str2 = [str1 copy]; // 地址和Str1一样
NSString *str3 = [str1 mutableCopy]; // 地址和str1不同, 虽然是深拷贝,但无法修改str3内容(语法不通过)
NSMutableString *str4 = [str1 copy]; // 地址和Str一样, 修改Str4会崩溃
NSMutableString *str5 = [str1 mutableCopy]; // 地址和str1 不同

NSLog(@"str1 ===== %p", str1);
NSLog(@"str2 ===== %p", str2);
NSLog(@"str3 ===== %p", str3);
NSLog(@"str4 ===== %p", str4);
NSLog(@"str5 ===== %p", str5);

[str3 appendString:@"xxx"]; // 报错,语法错误
[str4 appendString:@"xxx"]; // 会导致程序崩溃. reason: ‘Attempt to mutate immutable object with appendString:‘

　　 NSMutableString *str1 = [NSMutableString stringWithFormat:@"abc"];
    NSString *str2 = [str1 copy]; // 地址和Str1不同
    NSString *str3 = [str1 mutableCopy]; // 地址和str1不同, 虽然是深拷贝,但无法修改str3内容(语法不通过)
    NSMutableString *str4 = [str1 copy]; // 地址和Str1不同, str4本质是NSString而不是NSMutableString, 修改Str4会崩溃
    NSMutableString *str5 = [str1 mutableCopy]; // 地址和str1 不同

    NSLog(@"str1 ===== %p", str1);
    NSLog(@"str2 ===== %p", str2);
    NSLog(@"str3 ===== %p", str3);
    NSLog(@"str4 ===== %p", str4);
    NSLog(@"str5 ===== %p", str5);

NSArray *array1 = [NSArray arrayWithObjects:[NSMutableString stringWithFormat:@"a"], @"b", @"c", nil];
NSArray *array2 = [array1 copy]; // 地址与array1一样
NSArray *array3 = [array1 mutableCopy]; // 地址与array1不同
NSMutableArray *array4 = [array1 copy]; // 地址与array1一样

NSMutableArray *array5 = [array1 mutableCopy]; // 地址与array1不样

NSArray *array6 = [[NSArray alloc] initWithArray:array1 copyItems:YES]; // 地址与array1不同, 容器内的可变元素深拷贝, 而不可变元素依然是浅拷贝.

NSArray *array7 = [NSKeyedUnarchiver unarchiveObjectWithData:[NSKeyedArchiver archivedDataWithRootObject:array1]]; // 地址与array1不同, 容器内的元素都进行深拷贝

NSMutableString *str = array5[0];

[str appendString:@"xxx"];

NSMutableString *str2 = array5[1];

// [str2 appendString:@"xxx"]; // 会导致程序崩溃.

NSLog(@"array1 ==== %p", array1);

NSLog(@"array2 ==== %p", array2);

NSLog(@"array3 ==== %p", array3);

NSLog(@"array4 ==== %p", array4);

NSLog(@"array5 ==== %p", array5);

NSLog(@"array6 ==== %p", array6);

NSLog(@"array7 ==== %p", array7);

NSLog(@"array1[0] ==== %p", array1[0]);

NSLog(@"array2[0] ==== %p", array2[0]);

NSLog(@"array3[0] ==== %p", array3[0]);

NSLog(@"array4[0] ==== %p", array4[0]);

NSLog(@"array5[0] ==== %p", array5[0]);

NSLog(@"array6[0] ==== %p", array6[0]);

NSLog(@"array7[0] ==== %p", array7[0]);

NSLog(@"array1[1] ==== %p", array1[1]);

NSLog(@"array2[1] ==== %p", array2[1]);

NSLog(@"array3[1] ==== %p", array3[1]);

NSLog(@"array4[1] ==== %p", array4[1]);

NSLog(@"array5[1] ==== %p", array5[1]);

NSLog(@"array6[1] ==== %p", array6[1]);

NSLog(@"array7[1] ==== %p", array7[1]);

NSLog(@"array1[0] ==== %@", array1[0]);

NSLog(@"array2[0] ==== %@", array2[0]);

NSLog(@"array3[0] ==== %@", array3[0]);

NSLog(@"array4[0] ==== %@", array4[0]);

NSLog(@"array5[0] ==== %@", array5[0]);

NSLog(@"array6[0] ==== %@", array6[0]);

NSLog(@"array7[0] ==== %@", array7[0]);