iOS UILabel兩端對齊的實現（可包括中英文/數字）

- (void)conversionCharacterInterval:(NSInteger)maxInteger current:(NSString *)currentString withLabel:(UILabel *)label
{
    CGRect rect = [[currentString substringToIndex:1] boundingRectWithSize:CGSizeMake(200,label.frame.size.height)
                                     options:NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading
                                  attributes:@{NSFontAttributeName: label.font}
                                     context:nil];
    
    
    NSMutableAttributedString *attrString = [[NSMutableAttributedString alloc] initWithString:currentString];
    float strLength = [self getLengthOfString:currentString];
    [attrString addAttribute:NSKernAttributeName value:@(((maxInteger - strLength) * rect.size.width)/(strLength - 1)) range:NSMakeRange(0, strLength)];
    label.attributedText = attrString;
}

-  (float)getLengthOfString:(NSString*)str {
    
    float strLength = 0;
    char *p = (char *)[str cStringUsingEncoding:NSUnicodeStringEncoding];
    for (NSInteger i = 0 ; i < [str lengthOfBytesUsingEncoding:NSUnicodeStringEncoding]; i++) {
        if (*p) {
            strLength++;
        }
        p++;
    }
    return strLength/2;
}

注：中文字符長度1，英文字符及數字長度0.5