iOS @功能的部分实现思路

 1 - (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text{
 2     //判断键入的字符
 3     if ([text isEqualToString:@"@"]) {
 4         //触发相关功能
 5         //[self pickRemaidBtnClick];
 6         return NO;
 7     }
 8 
 9     return YES;
10 }

#define kATRegular @"@[\\u4e00-\\u9fa5\\w\\-\\_]+ "

+ (NSArray *) getMatchsWithStr : (NSString *) text {
    // 找到文本中所有的@
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:kATRegular options:NSRegularExpressionCaseInsensitive error:nil];
    NSArray *matches = [regex matchesInString:text options:NSMatchingReportProgress range:NSMakeRange(0, [text length])];
    return matches;
}

-(void)textViewDidChange:(UITextView *)textView {
    NSArray *matchs = [RemaidUserUtils getMatchsWithStr:textView.text];
    //改色
    [textView.textStorage addAttribute:NSForegroundColorAttributeName value:[UIColor colorWithHexString:@"#333333"] range:NSMakeRange(0, textView.text.length)];
    for (NSTextCheckingResult *match in matchs)
    {
        [textView.textStorage addAttribute:NSForegroundColorAttributeName value:BLUECOLOR range:NSMakeRange(match.range.location, match.range.length - 1)];
    }
}

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text{

    if ([text isEqualToString:@""])
    {
        NSRange selectRange = textView.selectedRange;
        if (selectRange.length > 0)
        {
            //用户长按选择文本时不处理
            return YES;
        }
        
        // 判断删除的是一个@中间的字符就整体删除
        NSMutableString *string = [NSMutableString stringWithString:textView.text];
        NSArray *matches = [RemaidUserUtils getMatchsWithStr:string];
        
        BOOL inAt = NO;
        NSInteger index = range.location;
        for (NSTextCheckingResult *match in matches)
        {
            NSRange newRange = NSMakeRange(match.range.location + 1, match.range.length - 1);
            if (NSLocationInRange(range.location, newRange))
            {
                inAt = YES;
                index = match.range.location;
                [textView.textStorage replaceCharactersInRange:match.range withString:@""];
                textView.selectedRange = NSMakeRange(index, 0);
                [self textViewDidChange:textView];
                return NO;
                break;
            }
        }
    }
    
    return YES;
}

- (void)textViewDidChangeSelection:(UITextView *)textView {
    // 光标不能点落在@词中间
    NSRange range = textView.selectedRange;
    if (range.length > 0)
    {
        // 选择文本时可以
        return;
    }
    
    NSArray *matches = [RemaidUserUtils getMatchsWithStr:textView.text];
    
    for (NSTextCheckingResult *match in matches)
    {
        NSRange newRange = NSMakeRange(match.range.location + 1, match.range.length - 1);
        if (NSLocationInRange(range.location, newRange))
        {
            if (range.location == match.range.location + 1) {
                textView.selectedRange = NSMakeRange(match.range.location + match.range.length, 0);
            } else {
                textView.selectedRange = NSMakeRange(match.range.location , 0);
            }
            break;
        }
    }
}