NSMutableString *string = [NSMutableString stringWithString: @"origion"]; //retainCount = 2 string
// NSMutableString *string1 = [@"origion" copy]; //巨大的数
// NSString *stringCopy = [string copy]; //retainCount = 2 string stringCopy retainCount = 1
// NSMutableString *mStringCopy = [string copy]; //retainCount = 2 string mStringCopy retainCount = 1
// NSMutableString *stringMCopy = [string mutableCopy];
//// [mStringCopy appendString:@"mm"];//error
// [string appendString:@" origion!"];
// [stringMCopy appendString:@"!!"];
(把不可变变量进行拷贝成可变变量时也是深拷贝)
1.copy在对可变变量进行拷贝时,是深拷贝,但是将NSString拷贝成NSString这种的时候和retain时一样的
2.再对NSArray时或者NSMutableArray时,只能深拷贝元素的指针,元素的内容无法深拷贝。