先上效果图：
UIFont * font1 = [UIFont systemFontOfSize:40];
UIFont * font2 = [UIFont systemFontOfSize:20];
NSMutableAttributedString * att = [[NSMutableAttributedString alloc] init];
NSAttributedString * att1 = [[NSAttributedString alloc] initWithString:@"20." attributes:@{NSFontAttributeName :font1,NSForegroundColorAttributeName:[UIColor orangeColor]}];
NSAttributedString * att2 = [[NSAttributedString alloc] initWithString:@"00" attributes:@{NSFontAttributeName:font2,NSForegroundColorAttributeName:[UIColor orangeColor]}];
NSAttributedString * att3 = [[NSAttributedString alloc] initWithString:@"%" attributes:@{NSFontAttributeName:font2,NSForegroundColorAttributeName:[UIColor orangeColor],NSBaselineOffsetAttributeName:@15}];
[att appendAttributedString:att1];
[att appendAttributedString:att2];
[att appendAttributedString:att3];
self.myLab.attributedText = att;