内存管理与copy和mutableCopy

最新推荐文章于 2022-03-30 16:02:36 发布

adsl2812358

最新推荐文章于 2022-03-30 16:02:36 发布

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本文链接：https://blog.youkuaiyun.com/adsl2812358/article/details/47089443

本文通过实验演示了Objective-C中浅拷贝与深拷贝的区别，特别关注NSString、NSArray、NSDictionary等对象的拷贝行为及Student自定义类的实现。

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#import <Foundation/Foundation.h>

#import "Student.h"

int main(int argc,constchar * argv[]) {

NSString *str =@"123456";

NSString *strCopy = [strcopy];

NSString *strMCopy = [strmutableCopy];

NSLog(@"%p, %2ld", str, str.retainCount);

NSLog(@"%p, %2ld", strCopy, strCopy.retainCount);

NSLog(@"%p, %2ld", strMCopy, strMCopy.retainCount);

NSLog(@"\n");

// 2015-07-27 18:35:44.418 TEXT[4933:148940] 0x100002050, -1

// 2015-07-27 18:35:44.419 TEXT[4933:148940] 0x100002050, -1

// 2015-07-27 18:35:44.419 TEXT[4933:148940] 0x100204c60, 1

NSArray *arr =@[@"1",@"2"];

NSArray *arrCopy = [arrcopy];

NSArray *arrMCopy = [arrmutableCopy];

NSLog(@"%p, %2ld", arr, arr.retainCount);

NSLog(@"%p, %2ld", arrCopy, arrCopy.retainCount);

NSLog(@"%p, %2ld", arrMCopy, arrMCopy.retainCount);

NSLog(@"\n");

// 2015-07-27 18:35:44.419 TEXT[4933:148940]

// 2015-07-27 18:35:44.420 TEXT[4933:148940] 0x1003001f0, 2

// 2015-07-27 18:35:44.420 TEXT[4933:148940] 0x100300000, 1

NSDictionary *dic =@{@"1" :@"2"};

NSDictionary *dicCopy = [diccopy];

NSMutableDictionary *dicMCopy = [dicmutableCopy];

NSLog(@"%p, %2ld", dic, dic.retainCount);

NSLog(@"%p, %2ld", dicCopy, dicCopy.retainCount);

NSLog(@"%p, %2ld", dicMCopy, dicMCopy.retainCount);

NSLog(@"\n");

// 2015-07-27 18:35:44.420 TEXT[4933:148940] 0x100300580, 2

// 2015-07-27 18:35:44.420 TEXT[4933:148940] 0x100300850, 1

NSMutableString *mStr = [strmutableCopy];

NSMutableString *mStrMCopy = [mStrmutableCopy];

NSLog(@"%p, %2ld", mStr, mStr.retainCount);

NSLog(@"%p, %2ld", mStrMCopy, mStrMCopy.retainCount);

NSLog(@"\n");

// 2015-07-27 18:35:44.421 TEXT[4933:148940] 0x100400420, 1

// 2015-07-27 18:35:44.421 TEXT[4933:148940] 0x100400500, 1

NSMutableArray *mArr = [arrmutableCopy];

NSMutableArray *mArrCopy = [mArrcopy];

NSMutableArray *mArrMCopy = [mArrmutableCopy];

NSLog(@"%p, %2ld", mArr, mArr.retainCount);

NSLog(@"%p, %2ld", mArrCopy, mArrCopy.retainCount);

NSLog(@"%p, %2ld", mArrMCopy, mArrMCopy.retainCount);

NSLog(@"\n");

// 2015-07-27 18:35:44.421 TEXT[4933:148940] 0x100106a50, 1

// 2015-07-27 18:35:44.421 TEXT[4933:148940] 0x10010ca10, 1

// 2015-07-27 18:35:44.421 TEXT[4933:148940] 0x10010ca30, 1

Student *stu = [StudentstudentWithName:@"xiaolei"andScore:66];

Student *stuCopy = [stucopy];

Student *stuMCopy = [stumutableCopy];

NSLog(@"%p, %ld", stu, stu.retainCount);

NSLog(@"%p, %ld", stuCopy, stuCopy.retainCount);

NSLog(@"%p, %ld", stuMCopy, stuMCopy.retainCount);

// 2015-07-27 19:07:07.222 TEXT[5185:159328] 0x100110510, 2

// 2015-07-27 19:07:07.237 TEXT[5185:159328] 0x1001109b0, 1

return0;

}

*copy 可变的全是浅copy,只copy地址自身retainCount+1.不可变的copy 和mutableCopy全是深拷贝 alloc出新的对象*

#import <Foundation/Foundation.h>

@interface Student :NSObject<NSCopying,NSMutableCopying>

@property(nonatomic,copy)NSString *name;

@property(nonatomic,retain)NSMutableArray *arr;

@property(nonatomic,assign)CGFloat score;

- (instancetype)initWithName:(NSString *)name

andScore:(CGFloat)score;

+ (Student *)studentWithName:(NSString *)name

andScore:(CGFloat)score;

@end

#import "Student.h"

@implementation Student

- (instancetype)initWithName:(NSString *)name

andScore:(CGFloat)score{

self = [superinit];

if (self) {

self.name = name;

self.score = score;

self.arr = [NSMutableArrayarray];

}

return self;

}

+ (Student *)studentWithName:(NSString *)name

andScore:(CGFloat)score{

Student *stu = [[Studentalloc]initWithName:nameandScore:score];

return stu;

}

- (void)dealloc{

[_arrrelease];

[_namerelease];

[superdealloc];

}

- (id)copyWithZone:(NSZone *)zone{

return [self retain];

}

- (id)mutableCopyWithZone:(NSZone *)zone{

Student *stu = [StudentallocWithZone:zone];

stu.name =_name;

stu.score =_score;

stu.arr =_arr;

return [stu autorelease];

}

@end

注:只是试验下浅copy

***谁创建谁释放***

*+1-1要相等*