iOS之属性修饰符 retain、strong和copy区别测试

时不时会有点迷惑属性修饰符retain、strong、copy三者之间的区别，还是把测试过程记录下来好一点！

一、属性修饰符retain、strong、copy修饰字符串测试

先看代码，创建一个Person类，定义属性

#import <Foundation/Foundation.h>

@interface Person : NSObject

@property (nonatomic, retain) NSString *strRetain;
@property (nonatomic, strong) NSString *strStrong;
@property (nonatomic, copy) NSString *strCopy;
@property (nonatomic, retain) NSMutableString *strMutableRetain;
@property (nonatomic, strong) NSMutableString *strMutableStrong;
@property (nonatomic, copy) NSMutableString *strMutableCopy;

@end

测试代码：

 1 Person *per = [[Person alloc] init];
 2     NSString *name = @"原XM";
 3     [per setStrRetain:name];
 4     [per setStrStrong:name];
 5     per.strCopy = name;
 6     
 7     NSMutableString *name2 = [[NSMutableString alloc] initWithString:@"原XM2"];
 8     per.strMutableRetain = name2;
 9     per.strMutableStrong = name2;
10     per.strMutableCopy = name2;
11     
12     NSLog(@"------ 改变之前打印 ------");
13     NSLog(@"per.strRetain: %@, ", per.strRetain);
14     NSLog(@"per.strStrong: %@", per.strStrong);
15     NSLog(@"per.strCopy: %@", per.strCopy);
16     NSLog(@"per.strMutableRetain: %@", per.strMutableRetain);
17     NSLog(@"per.strMutableStrong: %@", per.strMutableStrong);
18     NSLog(@"per.strMutableCopy: %@", per.strMutableCopy);
19     
20     name = @"新XM";
21     [name2 appendString:@"新XM2"];
22     
23     NSLog(@"------- 改变之后打印 -------");
24     NSLog(@"per.strRetain: %@", per.strRetain);
25     NSLog(@"per.strStrong: %@", per.strStrong);
26     NSLog(@"per.strCopy: %@", per.strCopy);
27     NSLog(@"per.strMutableRetain: %@", per.strMutableRetain);
28     NSLog(@"per.strMutableStrong: %@", per.strMutableStrong);
29     NSLog(@"per.strMutableCopy: %@", per.strMutableCopy);

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