ios copy 和 retain 字符串

  1 @property (retain, nonatomic) NSString *retainStr;
  2 @property (copy, nonatomic)   NSString *copyStr;
  3
  4
  5
  6 @property (retain, nonatomic) NSMutableString *retainMStr;
  7 @property (copy, nonatomic)   NSMutableString *copyMStr;
  8
  9
 10
 11 实现代码如下：
 12
 13     NSMutableString *mStr = [NSMutableString string];
 14
 15     [mStr setString:@"我没变"];
 16
 17
 18
 19     self.retainStr   = mStr;
 20
 21     self.copyStr     = mStr;
 22
 23     self.retainMStr = mStr;
 24
 25     self.copyMStr   = mStr;
 26
 27
 28
 29     NSLog(@"retainStr:%@",  self.retainStr);
 30
 31     NSLog(@"copyStr:%@",    self.copyStr);
 32
 33     NSLog(@"retainMStr:%@", self.retainMStr);
 34
 35     NSLog(@"copyMStr:%@",   self.copyMStr);
 36
 37     NSLog(@"\n");
 38
 39
 40
 41     [mStr setString:@"我变了"];
 42
 43
 44
 45     NSLog(@"retainStr:%@",  self.retainStr);
 46
 47     NSLog(@"copyStr:%@",    self.copyStr);
 48
 49     NSLog(@"retainMStr:%@", self.retainMStr);
 50
 51     NSLog(@"copyMStr:%@",   self.copyMStr);
 52
 53     NSLog(@"\n");
 54
 55
 56
 57     NSString *str = @"我来了";//[[NSString alloc] initWithFormat:@"我来了"];//两种方式都一样。
 58
 59     self.retainStr  = str;
 60
 61     self.copyStr    = str;
 62
 63     self.retainMStr = [str mutableCopy];
 64
 65     self.copyMStr   = [str mutableCopy];
 66
 67
 68
 69     NSLog(@"retainStr:%@",  self.retainStr);
 70
 71     NSLog(@"copyStr:%@",    self.copyStr);
 72
 73     NSLog(@"retainMStr:%@", self.retainMStr);
 74
 75     NSLog(@"copyMStr:%@",   self.copyMStr);
 76
 77     NSLog(@"\n");
 78
 79
 80
 81     str =@"我走了";//[[NSStringalloc] initWithFormat:@"我走了"];//两种方式都一样
 82
 83
 84
 85     NSLog(@"retainStr:%@",  self.retainStr);
 86
 87     NSLog(@"copyStr:%@",    self.copyStr);
 88
 89     NSLog(@"retainMStr:%@", self.retainMStr);
 90
 91     NSLog(@"copyMStr:%@",   self.copyMStr);
 92
 93     NSLog(@"\n");
 94
 95
 96
 97 打印结果如下：
 98
 99 2012-10-12 13:53:14.858 StringDemo[1515:11303] retainStr:我没变
100
101 2012-10-12 13:53:14.860 StringDemo[1515:11303] copyStr:我没变
102
103 2012-10-12 13:53:14.861 StringDemo[1515:11303] retainMStr:我没变
104
105 2012-10-12 13:53:14.862 StringDemo[1515:11303] copyMStr:我没变
106
107 2012-10-12 13:53:14.863 StringDemo[1515:11303]
108
109 2012-10-12 13:53:14.864 StringDemo[1515:11303] retainStr:我变了
110
111 2012-10-12 13:53:14.865 StringDemo[1515:11303] copyStr:我没变
112
113 2012-10-12 13:53:14.866 StringDemo[1515:11303] retainMStr:我变了
114
115 2012-10-12 13:53:14.867 StringDemo[1515:11303] copyMStr:我没变
116
117 2012-10-12 13:53:14.868 StringDemo[1515:11303]
118
119 2012-10-12 13:53:14.869 StringDemo[1515:11303] retainStr:我来了
120
121 2012-10-12 13:53:14.869 StringDemo[1515:11303] copyStr:我来了
122
123 2012-10-12 13:53:14.870 StringDemo[1515:11303] retainMStr:我来了
124
125 2012-10-12 13:53:14.871 StringDemo[1515:11303] copyMStr:我来了
126
127 2012-10-12 13:53:14.872 StringDemo[1515:11303]
128
129 2012-10-12 13:53:14.873 StringDemo[1515:11303] retainStr:我来了
130
131 2012-10-12 13:53:14.874 StringDemo[1515:11303] copyStr:我来了
132
133 2012-10-12 13:53:14.875 StringDemo[1515:11303] retainMStr:我来了
134
135 2012-10-12 13:53:14.876 StringDemo[1515:11303] copyMStr:我来了

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