objective-c - NSString从return方法返回空

Question

我有一个不寻常的问题，我不知道为什么:

我有以下方法:

 - (NSString*) copyAndReplaceOccurencesForProfileFromString: (NSString*)initialString toString:(NSString*)aString
{

        aString = [NSString stringWithString:initialString];
        DLog(@"PROFILE INITIAL HTML STRING: %@", initialString);

        aString = [aString stringByReplacingOccurrencesOfString:@"//PROFILE_IMAGE//" withString:profileImageForHTML];
        aString = [aString stringByReplacingOccurrencesOfString:@"//PROFILE_NAME//" withString:profileBirthNameString];
        aString = [aString stringByReplacingOccurrencesOfString:@"//PROFILE_BIRTHDATE//" withString:profileDateOfBirthString];
        return aString;
    }

像这样被称为:

    NSString *profileSection = [NSString string];
[self copyAndReplaceOccurencesForProfileFromString:htmlBody_profile toString:profileSection];
DLog(@"PROFILE MODIFIED HTML STRING: %@", profileSection);

但“profileSection”字符串返回空。

我必须指出，在调用return之前，“aString”中包含值。

知道为什么会这样吗？
谢谢 !

Answer 1

编辑:看一下

   NSString *profileSection = [NSString string]; //reference created

再次当profileSection作为aString传入方法时:

   aString = [NSString stringWithString:initialString]; //new reference created

现在profileSection永远无法容纳引用不同的字符串。

使您的函数返回一个新的NSString。

- (NSString*) copyAndReplaceOccurencesForProfileFromString: (NSString*)initialString
{
        NSString *aString = [NSString stringWithString:initialString];
        DLog(@"PROFILE INITIAL HTML STRING: %@", initialString);

        aString = [aString stringByReplacingOccurrencesOfString:@"//PROFILE_IMAGE//" withString:profileImageForHTML];
        aString = [aString stringByReplacingOccurrencesOfString:@"//PROFILE_NAME//" withString:profileBirthNameString];
        aString = [aString stringByReplacingOccurrencesOfString:@"//PROFILE_BIRTHDATE//" withString:profileDateOfBirthString];
        return aString;
}

现在使用像:

NSString *profileSection = [self copyAndReplaceOccurencesForProfileFromString:htmlBody_profile];
DLog(@"PROFILE MODIFIED HTML STRING: %@", profileSection);