浅谈iOS中几个常用协议NSCopying/NSMutableCopying

NSMutableString *test1 = [[NSMutableString alloc]initWithString:@"11111"];
NSMutableString *test2 = [test1 copy];
[test2 appendString:@"22222"];

NSString *test3 = @"111111";
NSString *test4 = [test3 copy];
NSMutableString *test5 = [test3 mutableCopy];
NSLog(@"test3 is %p, test4 is %p, tast5 is %p",test3,test4,test5);
test3 is 0x10d6bb3a8, test4 is 0x10d6bb3a8, tast5 is 0x600000073e80

NSMutableString *test11 = [[NSMutableString alloc]initWithString:@"444444"];
NSString *test12 = [test11 copy]; 
NSMutableString *test13 = [test11 mutableCopy]; 
NSLog(@"test11 is %p, test12 is %p, tast13 is %p",test11,test12,test13);
 
test11 is 0x600000073e00, test12 is 0xa003434343434346, tast13 is 0x600000073dc0

NSArray *array = [NSArray arrayWithObjects:@"1", nil];
NSArray *copyArray = [array copy];
NSMutableArray *mutableCopyArray = [array mutableCopy];
NSLog(@"array is %p, copyArray is %p, mutableCopyArray is %p", array, copyArray, mutableCopyArray);
array is 0x60800001e580, copyArray is 0x60800001e580, mutableCopyArray is 0x608000046ea0

NSMutableArray *element = [NSMutableArray arrayWithObject:@1];
NSMutableArray *array = [NSMutableArray arrayWithObject:element];
NSArray *copyArray = [array copy];
NSMutableArray *mutableCopyArray = [array mutableCopy];
NSLog(@"array is %p, copyArray is %p, mutableCopyArray is %p", array, copyArray, mutableCopyArray);
[mutableCopyArray[0] addObject:@2];
NSLog(@"element is %@, array is %@, copyArray is %@, mutableCopyArray is %@", element,array,copyArray, mutableCopyArray);
 
2017-02-22 11:53:25.286 test[91520:3915695] array is 0x600000057670, copyArray is 0x600000000bc0, mutableCopyArray is 0x6080000582a0
2017-02-22 11:53:25.287 test[91520:3915695] element is (
1,
2
), array is (
 (
 1,
 2
)
), copyArray is (
 (
 1,
 2
)
), mutableCopyArray is (
 (
 1,
 2
)
)

@interface Person : NSObject 
@property (nonatomic, copy) NSString *familyname;
@property (nonatomic, strong) NSString *nickname;
@end
Person *p1 = [[Person alloc]init];
 
NSMutableString *familyname = [[NSMutableString alloc]initWithString:@"张三"];
p1.familyname = familyname;
[familyname appendString:@"峰"];
 
NSLog(@"p1.familyname is %@",p1.familyname);
 
NSMutableString *nickname = [[NSMutableString alloc]initWithString:@"二狗"];
p1.nickname = nickname;
[nickname appendString:@"蛋儿"];
 
NSLog(@"p1.nickname is %@", p1.nickname);
2017-02-22 13:53:58.979 test[98299:3978965] p1.familyname is 张三
2017-02-22 13:53:58.979 test[98299:3978965] p1.nickname is 二狗蛋儿

NSCopying协议中的方法只有一个，如下：
- (id)copyWithZone:(NSZone *)zone { 
 Person *model = [[[self class] allocWithZone:zone] init];
 model.firstName = self.firstName;
 model.lastName = self.lastName;
 //未公开的成员
 model->_nickName = _nickName;
 return model;
}

- (id)copyWithZone:(NSZone *)zone {
 AFHTTPRequestSerializer *serializer = [[[self class] allocWithZone:zone] init];
 serializer.mutableHTTPRequestHeaders = [self.mutableHTTPRequestHeaders mutableCopyWithZone:zone];
 serializer.queryStringSerializatiOnStyle= self.queryStringSerializationStyle;
 serializer.queryStringSerialization = self.queryStringSerialization;
 
 return serializer;
}