1、 copy、mutableCopy方法
copy方法返回对象的不可修改的副本
mutableCopy方法返回的对象可修改的副本
1)、测试demo
int main(int argc, char * argv[]) { @autoreleasepool { NSMutableString *book = [NSMutableString stringWithString:@"chenyu"]; NSMutableString *bookCopy = [book mutableCopy]; [bookCopy replaceCharactersInRange:NSMakeRange(1, 2) withString:@"gong"]; NSLog(@"book is %@", book); NSLog(@"bookCopy is %@", bookCopy); NSString *str = @"chenyu"; NSMutableString *strCopy = [str mutableCopy]; [strCopy appendString:@"chenyu"]; NSLog(@"strCopy is:%@", strCopy); //由于str2是不可变的，所以运行下面会报错 NSMutableString *str2 = [str copy]; NSLog(@"str copy chen is:%@", str2); // [str2 appendString:@"chenyu"]; } }
2)、运行结果
2018-07-15 19:03:35.564049+0800 cyTest[27254:9418105] book is chenyu 2018-07-15 19:03:35.565157+0800 cyTest[27254:9418105] bookCopy is cgongnyu 2018-07-15 19:03:35.566056+0800 cyTest[27254:9418105] strCopy is:chenyuchenyu 2018-07-15 19:03:35.566857+0800 cyTest[27254:9418105] str copy chen is:chenyu
2、NSCopying、NSMutableCopy协议
对象调用copy方法来复制自身的可变副本，需要类 实现NSCopying协议，让该类实现copyWithZone方法
对象调用mutableCopy方法来复制自身的可变副本，需要类实现NSMutbaleCopying协议，让类实现mutableCopyWithZone方法demo可以看下下面写的浅复制
3、深复制和浅复制
我个人理解感觉浅复制是复制后的属性(指针变量)指向的地址都是同一块地址，当复制后的对象属性值发生变化的时候，原始值也发生了变化。
深复制就是复制后的属性(指针变量)指向的地址不是同一块地址，当复制后的对象属性值发生变化的时候，原始值不会发生变化。
1)、浅复制测试Demo
Dog.h
#import <Foundation/Foundation.h> #ifndef Dog_h #define Dog_h @interface Dog : NSObject<NSCopying> @property (nonatomic, strong) NSMutableString *name; @property (nonatomic, assign) int age; @end #endif /* Dog_h */
Dog.m
#import <Foundation/Foundation.h> #import "Dog.h" @implementation Dog @synthesize name; @synthesize age; -(id)copyWithZone:(NSZone *)zone { Dog *dog = [[[self class] allocWithZone:zone] init]; dog.name = self.name; dog.age = self.age; return dog; } @end
main.m
Dog *dog1 = [Dog new]; dog1.name = [NSMutableString stringWithString:@"chen"]; dog1.age = 1; NSLog(@"dog1.name is %@ and age is %d", dog1.name, dog1.age); //浅复制 Dog *dog2 = [dog1 copy]; // dog2.name = [NSMutableString stringWithString:@"li"]; [dog2.name replaceCharactersInRange:NSMakeRange(1, 2) withString:@"hel"]; dog2.age = 20; NSLog(@"dog2.name is %@ and age is %d", dog2.name, dog2.age); NSLog(@"dog1.name is %@ and age is %d", dog1.name, dog1.age);
2)、运行结果
2018-07-15 19:03:35.567556+0800 cyTest[27254:9418105] dog1.name is chen and age is 1 2018-07-15 19:03:35.567690+0800 cyTest[27254:9418105] dog2.name is cheln and age is 20 2018-07-15 19:03:35.567768+0800 cyTest[27254:9418105] dog1.name is cheln and age is 1
