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IOS学习笔记十八(copy、mutableCopy、NSCopying、NSMutableCopy、深复制、浅复制)

發(fā)布時(shí)間：2023/12/4 编程问答 36 豆豆

生活随笔收集整理的這篇文章主要介紹了 IOS学习笔记十八(copy、mutableCopy、NSCopying、NSMutableCopy、深复制、浅复制) 小編覺得挺不錯(cuò)的,現(xiàn)在分享給大家,幫大家做個(gè)參考.

1、 copy、mutableCopy方法

copy方法返回對象的不可修改的副本

mutableCopy方法返回的對象可修改的副本

1)、測試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是不可變的，所以運(yùn)行下面會報(bào)錯(cuò)NSMutableString *str2 = [str copy];NSLog(@"str copy chen is:%@", str2); // [str2 appendString:@"chenyu"];} }

2)、運(yùn)行結(jié)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

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2、NSCopying、NSMutableCopy協(xié)議

對象調(diào)用copy方法來復(fù)制自身的可變副本，需要類實(shí)現(xiàn)NSCopying協(xié)議，讓該類實(shí)現(xiàn)copyWithZone方法

對象調(diào)用mutableCopy方法來復(fù)制自身的可變副本，需要類實(shí)現(xiàn)NSMutbaleCopying協(xié)議，讓類實(shí)現(xiàn)mutableCopyWithZone方法demo可以看下下面寫的淺復(fù)制

3、深復(fù)制和淺復(fù)制

我個(gè)人理解感覺淺復(fù)制是復(fù)制后的屬性(指針變量)指向的地址都是同一塊地址，當(dāng)復(fù)制后的對象屬性值發(fā)生變化的時(shí)候，原始值也發(fā)生了變化。

深復(fù)制就是復(fù)制后的屬性(指針變量)指向的地址不是同一塊地址，當(dāng)復(fù)制后的對象屬性值發(fā)生變化的時(shí)候，原始值不會發(fā)生變化。

1)、淺復(fù)制測試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);//淺復(fù)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)、運(yùn)行結(jié)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

3)、深復(fù)制Demo

Dog.h文件一樣

Dog.m文件有點(diǎn)變化

#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.name = [self.name mutableCopy];dog.age = self.age;return dog; } @end

main.m文件一樣

Dog *dog1 = [Dog new];dog1.name = [NSMutableString stringWithString:@"chen"];dog1.age = 1;NSLog(@"dog1.name is %@ and age is %d", dog1.name, dog1.age);//深復(fù)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);

4)、運(yùn)行結(jié)果

2018-07-15 19:13:08.751335+0800 cyTest[27529:9427019] dog1.name is chen and age is 1 2018-07-15 19:13:08.751686+0800 cyTest[27529:9427019] dog2.name is cheln and age is 20 2018-07-15 19:13:08.751885+0800 cyTest[27529:9427019] dog1.name is chen and age is 1

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4、setter方法的復(fù)制選項(xiàng)

我們setter方法復(fù)制選項(xiàng)的時(shí)候，如果加了copy屬性，比如setName方法

-(void)setName : (NSMutableStrinfg *)name {self.name = [name copy];} #import <Foundation/Foundation.h> #import "Dog.h"@implementation Dog @synthesize name; @synthesize age; @end

所以當(dāng)對象設(shè)置了name屬性的話，就不能再改變了，如下demo

Dog.h

#import <Foundation/Foundation.h> #ifndef Dog_h #define Dog_h@interface Dog : NSObject @property (nonatomic, copy) 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; @end

main.m

Dog *dog1 = [Dog new];dog1.name = [NSMutableString stringWithString:@"chen"];dog1.age = 1;[dog1.name appendString:@"hello"];

運(yùn)行結(jié)果

2018-07-15 19:22:17.736557+0800 cyTest[27853:9436238] -[NSTaggedPointerString appendString:]: unrecognized selector sent to instance 0xa0000006e6568634 2018-07-15 19:22:17.739655+0800 cyTest[27853:9436238] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSTaggedPointerString appendString:]: unrecognized selector sent to instance 0xa0000006e6568634' *** First throw call stack: (0 CoreFoundation 0x0000000104fd61e6 __exceptionPreprocess + 2941 libobjc.A.dylib 0x000000010466b031 objc_exception_throw + 482 CoreFoundation 0x0000000105057784 -[NSObject(NSObject) doesNotRecognizeSelector:] + 1323 CoreFoundation 0x0000000104f58898 ___forwarding___ + 14324 CoreFoundation 0x0000000104f58278 _CF_forwarding_prep_0 + 1205 cyTest 0x0000000103d60438 main + 6006 libdyld.dylib 0x0000000108a2f955 start + 1 ) libc++abi.dylib: terminating with uncaught exception of type NSException (lldb)

很明顯，報(bào)錯(cuò)了。