浅析Objective-C 深浅拷贝
先了解下概念：
//// main.m// TTTT//// Created by NeuLion SH on 12-12-3.// Copyright (c) 2012年 NeuLion SH. All rights reserved.//#import <Foundation/Foundation.h>int main(int argc, const char * argv[]){ @autoreleasepool { //第一种：非容器类不可变对象 NSString *str1=@"one day"; NSLog(@"\n初始化赋值引用计数为::::%lu",str1.retainCount); NSString *strCopy1=[str1 retain]; printf("\n继续retain引用计数为:::%lu",str1.retainCount); NSString *strCopy2=[str1 copy]; printf("\n继续copy后引用计数为::::%lu",str1.retainCount); NSString *strCopy3=[str1 mutableCopy]; printf("\n继续mutableCopy后为:::%lu\n",str1.retainCount); printf("\n非容器类不可变对象\n原始地址::::::::::%p",str1); printf("\nretain复制::::::::%p",strCopy1); printf("\ncopy复制::::::::::%p",strCopy2); printf("\nmutableCopy复制:::%p",strCopy3); //这里说明该类型不存在引用计数的概念 // 初始化赋值引用计数为：18446744073709551615 // 继续retain引用计数为：18446744073709551615 // 继续copy后引用计数为：18446744073709551615 // 继续mutableCopy后为：18446744073709551615 //非容器类不可变对象 //原始地址::::::::::0x1000033d0 //retain复制::::::::0x1000033d0//浅复制 //copy复制::::::::::0x1000033d0//浅复制 //mutableCopy复制:::0x10010c420//深复制 printf("\n"); //第二种：容器类不可变数组 NSArray *array1= [NSArray arrayWithObjects:@"a",@"b",@"c",@"d",nil]; printf("\n初始化赋值引用计数为::::::::::::%lu",array1.retainCount); NSArray *arrayCopy1 = [array1 retain]; printf("\n继续retain后引用计数为:::::::::%lu",array1.retainCount); NSArray *arrayCopy2 = [array1 copy]; printf("\n继续copy后引用计数为:::::::::::%lu",array1.retainCount); NSArray *arrayCopy3 = [array1 mutableCopy]; printf("\n继续mutableCopy后引用计数为::::%lu\n",array1.retainCount); printf("\n容器类不可变数组\n原始地址::::::::::%p\t\t%p",array1,[array1 objectAtIndex:1]); printf("\nretain复制::::::::%p\t\t%p",arrayCopy1,[arrayCopy1 objectAtIndex:1]); printf("\ncopy复制::::::::::%p\t\t%p",arrayCopy2,[arrayCopy2 objectAtIndex:1]); printf("\nmutableCopy复制:::%p\t\t%p",arrayCopy3,[arrayCopy3 objectAtIndex:1]); //初始化赋值引用计数为::::::::::::1 //继续retain后引用计数为:::::::::2 //继续copy后引用计数为:::::::::::3 //继续mutableCopy后引用计数为::::3 //容器类不可变数组 //原始地址::::::::::0x10010c6b0 0x100003410 //retain复制::::::::0x10010c6b0 0x100003410//浅复制 //copy复制::::::::::0x10010c6b0 0x100003410//浅复制 //mutableCopy复制:::0x10010c760 0x100003410//深复制 printf("\n"); //第三种：非容器类可变对象 NSMutableString *str2=[NSMutableString stringWithString:@"two day"]; printf("\n初始化赋值引用计数为::::::::::::%lu",str2.retainCount); NSMutableString *strCpy1=[str2 retain]; printf("\n继续retain后引用计数为:::::::::%lu",str2.retainCount); NSMutableString *strCpy2=[str2 copy]; printf("\n继续copy后引用计数为:::::::::::%lu",str2.retainCount); NSMutableString *strCpy3=[str2 mutableCopy]; printf("\n继续mutableCopy后引用计数为::::%lu\n",str2.retainCount); printf("\n非容器类可变对象\n原始地址::::::::::%p",str2); printf("\nretin复制::::::::%p",strCpy1); printf("\ncopy复制::::::::::%p",strCpy2); printf("\nmutableCopy复制:::%p",strCpy3); //初始化赋值引用计数为::::::::::::1 //继续retain后引用计数为:::::::::2 //继续copy后引用计数为:::::::::::2 //继续mutableCopy后引用计数为::::2 //非容器类可变对象 //原始地址::::::::::0x10010c560 //retain复制::::::::0x10010c560//浅复制 //copy复制::::::::::0x100102720//深复制 //mutableCopy复制:::0x10010c880//深复制 printf("\n"); //第四种：容器类可变数组 NSMutableArray *array2 = [NSMutableArray arrayWithObjects:@"aa",@"bb",@"cc",@"dd",nil]; printf("\n初始化赋值引用计数为::::::::::%lu",array2.retainCount); NSMutableArray *arrayCpy1 = [array2 retain]; printf("\n继续retain后引用计数为:::::::%lu",array2.retainCount); NSMutableArray *arrayCpy2=[array2 copy]; printf("\n继续copy后引用计数为:::::::::%lu",array2.retainCount); NSMutableArray *arrayCpy3 = [array2 mutableCopy]; printf("\n继续mutableCopy后引用计数为::%lu\n",array2.retainCount); printf("\n容器类可变数组\n原始地址:::::::::::%p\t%p",array2,[array2 objectAtIndex:1]); printf("\nretain复制:::::::::%p\t%p",arrayCpy1,[arrayCpy1 objectAtIndex:1]); printf("\ncopy复制:::::::::::%p\t%p",arrayCpy2,[arrayCpy2 objectAtIndex:1]); printf("\nnmutableCopy复制:::%p\t%p",arrayCpy3,[arrayCpy3 objectAtIndex:1]); //初始化赋值引用计数为::::::::::1 //继续retain后引用计数为:::::::2 //继续copy后引用计数为:::::::::2 //继续mutableCopy后引用计数为::2 //容器类可变数组 //原始地址:::::::::::0x10010e6c0 0x1000034b0 //retain复制:::::::::0x10010e6c0 0x1000034b0//浅复制 //copy复制:::::::::::0x10010e790 0x1000034b0//深复制 //nmutableCopy复制:::0x10010e7c0 0x1000034b0//深复制 /////////////////////////////////// printf("\n"); //一、容器内的元素内容都是浅拷贝 NSArray *mArray1 = [NSArray arrayWithObjects:[NSMutableString stringWithString:@"a"],@"b",@"c",nil]; printf("\nmArray1 retain count: %ld",[mArray1 retainCount]); // 1 printf("\nretain复制:::::::::%p\t%p",mArray1,[mArray1 objectAtIndex:1]); NSArray *mArrayCopy2 = [mArray1 copy]; printf("\nmArray1 retain count: %ld",[mArray1 retainCount]); // 2 printf("\ncopy复制:::::::::::%p\t%p",mArrayCopy2,[mArrayCopy2 objectAtIndex:1]); // mArray1和mArrayCopy2指向同一对象，retain值+1 NSMutableArray *mArrayMCopy1 = [mArray1 mutableCopy]; printf("\nmArray1 retain count: %ld ",[mArray1 retainCount]); //2 printf("\nnmutableCopy复制:::%p\t%p \n",mArrayMCopy1,[mArrayMCopy1 objectAtIndex:1]); //mArrayCopy2和mArray1指向的是不一样的对象，但是其中的元素都是一样的对象----同一个指针 NSMutableString *testString = [mArray1 objectAtIndex:0]; //testString = @"1a1"; // 这样会改变testString的指针，其实是将@"1a1"临时对象赋给了testString [testString appendString:@"tail"]; // 这样以上三个数组的首元素都被改变了 NSLog(@"%@",mArray1); NSLog(@"%@",mArrayCopy2); NSLog(@"%@",mArrayMCopy1); // 由此可见，对于容器而言，其元素对象始终是指针复制。如果需要元素对象也是对象复制，就需要实现深拷贝。 /* mArray1 retain count: 1 retain复制:::::::::0x1005038200x100002150 mArray1 retain count: 2 copy复制:::::::::::0x1005038200x100002150 mArray1 retain count: 2 nmutableCopy复制:::0x1005038500x100002150 ( atail, b, c ) ( atail, b, c ) ( atail, b, c ) */ //二、 NSArray *array = [NSArray arrayWithObjects:[NSMutableString stringWithString:@"first"],[NSString stringWithString:@"b"],@"c",nil]; printf("\narray retain count: %ld",[array retainCount]); // 1 printf("\n原始:::::::::%p \t%p\t%p\t%p",array,[array objectAtIndex:0],[array objectAtIndex:1],[array objectAtIndex:2]); NSArray *deepCopyArray = [[NSArray alloc] initWithArray:array copyItems:YES]; printf("\narray retain count: %ld",[array retainCount]); // 1 printf("\ncopyItems:::::::::%p\t%p\t%p\t%p",deepCopyArray,[deepCopyArray objectAtIndex:0],[deepCopyArray objectAtIndex:1],[deepCopyArray objectAtIndex:2]); NSArray *trueDeepCopyArray = [NSKeyedUnarchiver unarchiveObjectWithData:[NSKeyedArchiver archivedDataWithRootObject:array]]; printf("\narray retain count: %ld",[array retainCount]); // 1 printf("\narchive:::::::::%p\t%p\t%p\t%p",trueDeepCopyArray,[trueDeepCopyArray objectAtIndex:0],[trueDeepCopyArray objectAtIndex:1],[trueDeepCopyArray objectAtIndex:2]); // trueDeepCopyArray是完全意义上的深拷贝，而deepCopyArray则不是，对于deepCopyArray内的不可变元素其还是指针复制。或者我们自己实现深拷贝的方法。因为如果容器的某一元素是不可变的，那你复制完后该对象仍旧是不能改变的，因此只需要指针复制即可。除非你对容器内的元素重新赋值，否则指针复制已足够。 // 举个例子，[[array objectAtIndex:0] appendString:@"sd"]后其他的容器内对象并不会受影响。[array objectAtIndex:1,2]和[deepCopyArray objectAtIndex:1,2]尽管是指向同一块内存，但是我们没有办法对其进行修改-----因为它是不可改变的。所以指针复制已经足够。所以这并不是完全意义上的深拷贝。 } return 0;}
#import <Foundation/Foundation.h>@interface NSDictionary (MutableDeepCopy)- (NSMutableDictionary *)mutableDeepCopy;@end#import "NSDictionary+MutableDeepCopy.h"@implementation NSDictionary (MutableDeepCopy)- (NSMutableDictionary *)mutableDeepCopy { NSMutableDictionary *returnDict = [[NSMutableDictionary alloc] initWithCapacity:[self count]]; NSArray *keys = [self allKeys]; for (id key in keys) { id oneValue = [self valueForKey:key]; id oneCopy = nil; if ([oneValue respondsToSelector:@selector(mutableDeepCopy)]) oneCopy = [oneValue mutableDeepCopy]; else if ([oneValue respondsToSelector:@selector(mutableCopy)]) oneCopy = [oneValue mutableCopy]; if (oneCopy == nil) oneCopy = [oneValue copy]; [returnDict setValue:oneCopy forKey:key]; } return returnDict;}@end
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