如何实现图片多种颜色的文字混排并且带的背景颜色范围比文字图片范围大

-(void)setRank:(NSUInteger) rank
{
    _rank = rank;
    UIColor *strokeColor = BGColorHex(C69116);
    NSUInteger tempRank = rank/10+1;
    if(0 == rank)
    {
        tempRank = 0;
    }
    else if(rank >= 100)
    {
        tempRank = 10;
    }
    switch (tempRank) {
        case 0:
            strokeColor = BGColorHex(A1A1A1);
            break;
        case 1:
            strokeColor = BGColorHex(FE7241);
            break;
        case 2:
            strokeColor = BGColorHex(FF9802);
            break;
        case 3:
            strokeColor = BGColorHex(FFBF01);
            break;
        case 4:
            strokeColor = BGColorHex(CBDC3C);
            break;
        case 5:
            strokeColor = BGColorHex(699E38);
            break;
        case 6:
            strokeColor = BGColorHex(26A99C);
            break;
        case 7:
            strokeColor = BGColorHex(05A8F3);
            break;
        case 8:
            strokeColor = BGColorHex(4F6BEA);
            break;
        case 9:
            strokeColor = BGColorHex(663CB5);
            break;
        case 10:
            strokeColor = BGColorHex(E9407B);
            break;
            
        default:
            break;
    }
    
    NSString *rankStr = [NSString stringWithFormat:@"%lu", rank];
    NSString *str = [NSString stringWithFormat:@"fron%@", rankStr];
    NSUInteger fillCharacterCount = 4;
    NSMutableAttributedString *textAttributedString = [[NSMutableAttributedString alloc] initWithString:str];
    [textAttributedString addAttribute:NSForegroundColorAttributeName value:[UIColor clearColor] range:NSMakeRange(0, fillCharacterCount)];
    [textAttributedString addAttribute:NSStrokeColorAttributeName value:strokeColor range:NSMakeRange(fillCharacterCount, rankStr.length)];
    [textAttributedString addAttribute:NSStrokeWidthAttributeName value:@4.0 range:NSMakeRange(fillCharacterCount, rankStr.length)];
   [textAttributedString addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:12.f] range:NSMakeRange(0, fillCharacterCount)];
   [textAttributedString addAttribute:NSFontAttributeName value:[UIFont boldSystemFontOfSize:12.f] range:NSMakeRange(fillCharacterCount, rankStr.length)];
    self.describeTitleLabel.attributedText = textAttributedString;
    [self.describeTitleLabel updateLayout];
    
    textAttributedString = [[NSMutableAttributedString alloc] initWithString:str];
    [textAttributedString addAttribute:NSForegroundColorAttributeName value:[UIColor clearColor] range:NSMakeRange(0, fillCharacterCount)];
    [textAttributedString addAttribute:NSForegroundColorAttributeName value:[UIColor whiteColor] range:NSMakeRange(fillCharacterCount, rankStr.length)];
    [textAttributedString addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:12.f] range:NSMakeRange(0, fillCharacterCount)];
    [textAttributedString addAttribute:NSFontAttributeName value:[UIFont boldSystemFontOfSize:12.f] range:NSMakeRange(fillCharacterCount, rankStr.length)];
    self.underDescribeTitleLabel.attributedText = textAttributedString;
    [self.underDescribeTitleLabel updateLayout];
    
    
    NSString *filename = [NSString stringWithFormat:@"lv%lu", tempRank];
    self.decribeImageView.image = [UIImage imageNamed:filename];
}