iOS开发 UIlabel 文字两边对齐

- (void)changeAlignmentRightandLeft{

CGRect textSize = [self.text boundingRectWithSize:CGSizeMake(self.frame.size.width, MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingTruncatesLastVisibleLine |NSStringDrawingUsesFontLeading attributes:@{NSFontAttributeName : self.font} context:nil];

CGFloat margin = (self.frame.size.width - textSize.size.width) / (self.text.length - 1);

NSNumber *number = [NSNumber numberWithFloat:margin];
NSMutableAttributedString *attributeString = [[NSMutableAttributedString alloc]initWithString:self.text];
[attributeString addAttribute:(id)kCTKernAttributeName value:number range:NSMakeRange(0, self.text.length - 1)];
self.attributedText = attributeString;

}