NSMutableString *string = [NSMutableString stringWithString: @"origion"]; //retainCount = 2 string
// NSMutableString *string1 = [@"origion" copy]; //巨大的數
// 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:@"!!"];
(把不可變變量進行拷貝成可變變量時也是深拷貝)
1.copy在對可變變量進行拷貝時,是深拷貝,但是將NSString拷貝成NSString這種的時候和retain時一樣的
2.再對NSArray時或者NSMutableArray時,只能深拷貝元素的指針,元素的內容無法深拷貝。