【深入浅出Objective-C】7.2单例和深拷贝

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1.单例：

#import <Foundation/Foundation.h>@interface MySingletonClass : NSObject@end

#import "MySingletonClass.h"@implementation MySingletonClassstatic MySingletonClass *shareSingletonObj = nil;+(MySingletonClass *)shareSingleton{    @synchronized(self){        if(shareSingletonObj == nil){            shareSingletonObj = [[super allocWithZone:NULL]init];        }else{            NSLog(@"shareSingletonObj is exist");        }    }    return nil;}//重写以下方法+(id)allocWithZone:(struct _NSZone *)zone{    return [[MySingletonClass shareSingleton]retain];}+(id)copyWithZone:(struct _NSZone *)zone{    return self;}-(id)retain{    return self;}-(oneway void)release{    }-(id)autorelease{    return self;}-(NSUInteger)retainCount{    return NSIntegerMax;}//end of 重写方法@end

2.NSArray和NSDictionary的深拷贝

NSArray:

#import <Foundation/Foundation.h>@interface NSArray (DeepCopy)-(NSMutableArray *)mutableDeepCopy;@end

#import "NSArray+DeepCopy.h"@implementation NSArray (DeepCopy)//NSArray的深拷贝-(NSMutableArray *)mutableDeepCopy{    NSMutableArray *arrRetain = [NSMutableArray arrayWithCapacity:self.count];    for(id obj in self){        id oneCopy = nil;        if([obj respondsToSelector:@selector(mutableDeepCopy)]){            oneCopy = [obj mutableDeepCopy];        }else if([obj respondsToSelector:@selector(mutableCopy)]){            oneCopy = [obj mutableCopy];        }else if([obj conformsToProtocol:@protocol(NSCopying)]){            oneCopy = [obj copy];        }else{            NSLog(@"%@",[obj class]);        }        [arrRetain addObject:obj];    }    return arrRetain;}@end

NSDictionary:

#import <Foundation/Foundation.h>@interface NSDictionary (DeepCopy)-(NSDictionary *)mutableDeepCopy;@end

#import "NSDictionary+DeepCopy.h"@implementation NSDictionary (DeepCopy)//NSDictionary的深拷贝-(NSMutableDictionary *)mutableDeepCopy{    NSMutableDictionary *dictRetain = [NSMutableDictionary dictionaryWithCapacity:self.count];    NSArray *allKeys = [self allKeys];        for(id key in allKeys){        id oneObj = [self objectForKey:key];        id oneCopy = nil;        if(!oneObj){            continue;        }        if([oneObj respondsToSelector:@selector(mutableDeepCopy)]){            oneCopy = [oneObj mutableDeepCopy];        }else if ([oneObj respondsToSelector:@selector(mutableCopy)]){            oneCopy = [oneObj mutableCopy];        }else if ([oneObj conformsToProtocol:@protocol(NSCopying)]){            oneCopy = [oneObj copy];        }else{            NSLog(@"ClassName = %@",[oneObj class]);            continue;        }        [dictRetain setObject:oneCopy forKey:key];    }    return dictRetain;}@end

#import <Foundation/Foundation.h>#import "NSArray+DeepCopy.h"#import "NSDictionary+DeepCopy.h"#define RELEASE(obj) if(obj){NSLog(@"obj = %@",obj);[obj release];obj = nil;}int main(int argc, const char * argv[]){            //1.内存的创建和释放        NSString *testObject = [[NSString alloc]initWithString:@"hello"];                RELEASE(testObject);//自定义宏，释放内存。                if(testObject){            NSLog(@"testObject = %@",testObject);            [testObject release];            testObject = nil;        }                                //2.copy和retain        //NSString遵循享元模式，所以地址一样。        NSString *strOrigin = @"hello";//0x0000000100001090        NSString *strA = [strOrigin copy];//0x0000000100001090        NSString *strB = [strOrigin retain];//0x0000000100001090        NSLog(@"%@",strA);        NSLog(@"%@",strB);                [strB release];        [strA release];        [strOrigin release];                //        NSMutableString *mm = [NSMutableString stringWithString:@"mutable String"];//0x0000000100103500        NSMutableString *m1 = [mm retain];//0x0000000100103500 retain只是引用计数加1        NSMutableString *m2 = [mm copy];//0x0000000100300670  copy是新的地址        NSLog(@"%@",mm);        NSLog(@"%@",m1);        NSLog(@"%@",m2);                //释放的顺序必须为m2,m1,mm        [m2 release];        [m1 release];        [mm release];                //3.深拷贝和浅拷贝        //假设一个NSArray中有三个NSString元素，当例用copy的时候，新的数组的指针确实是全新的，里面的三个元素也都还在，        //但其实，数组只是拷贝了原数组里面的指针        //没有对里面的元素进行拷贝。数组里的三个NString仍然指向原来的地址，这就是“浅拷贝”。                NSArray *arr = @[@"1",@"2",@"3"];        NSMutableArray *copyArr = [arr mutableDeepCopy];        NSLog(@"%@",arr);        NSLog(@"%@",copyArr);                [copyArr release];        [arr release];                        NSDictionary *dict = [NSDictionary dictionaryWithObject:@"value1" forKey:@"key1"];        NSDictionary *copyDict = [dict mutableDeepCopy];        NSLog(@"%@",dict);        NSLog(@"%@",copyDict);                [copyDict release];        [dict release];            return 0;}

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