解决使用NSMutableAttributedString 设置

• 问题描述
  使用NSMutableAttributedString设置不同字体，

int a = 50; int b = 10;
  NSMutableAttributedString *attStr = [[NSMutableAttributedString alloc] initWithString:@"10元抵现券"]; 
[attStr addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:a] range:NSMakeRange(0, 2)];
 [attStr addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:b] range:NSMakeRange(2, attStr.length - 2)];
// [attStr addAttribute:NSBaselineOffsetAttributeName value:@(0.36 * (a - b)) range:NSMakeRange(2, attStr.length - 2)]; 
label.attributedText = attStr;

文字不能居中对齐；如图：

• 解决方法
  NSMutableAttributedString 添加NSBaselineOffsetAttributeName这个Attribute

[attStr addAttribute:NSBaselineOffsetAttributeName value:@(0.36 * (a - b)) range:NSMakeRange(2, attStr.length - 2)];

value = 0.36 * (大字号 - 小字号)

 int a = 50; 
int b = 10; 
 NSMutableAttributedString *attStr = [[NSMutableAttributedString alloc] initWithString:@"10元抵现券"]; 
[attStr addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:a] range:NSMakeRange(0, 2)]; 
[attStr addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:b] range:NSMakeRange(2, attStr.length - 2)];
 [attStr addAttribute:NSBaselineOffsetAttributeName value:@(0.36 * (a - b)) range:NSMakeRange(2, attStr.length - 2)]; 
label.attributedText = attStr;

• 效果图 这里写图片描述