设置行间距(UILabel+Utils.m)

- (void)setText:(NSString*)text lineSpacing:(CGFloat)lineSpacing {
    if (lineSpacing < 0.01 || !text) {
        self.text = text;
        return;
    }

    NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:text];
    [attributedString addAttribute:NSFontAttributeName value:self.font range:NSMakeRange(0, [text length])];

    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    [paragraphStyle setLineSpacing:lineSpacing];
    [paragraphStyle setLineBreakMode:self.lineBreakMode];
    [paragraphStyle setAlignment:self.textAlignment];
    [attributedString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, [text length])];

    self.attributedText = attributedString;
}

UITextView+Utils.m

- (void)setText:(NSString*)text lineSpacing:(CGFloat)lineSpacing {
    if (lineSpacing < 0.01 || !text) {
        self.text = text;
        return;
    }

    NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:text];
    [attributedString addAttribute:NSFontAttributeName value:self.font range:NSMakeRange(0, [text length])];

    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    [paragraphStyle setLineSpacing:lineSpacing];
    [attributedString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, [attributedText length])];

    self.attributedText = attributedString;
}

计算行高的方法UILabel+Utils.m

+ (CGFloat)text:(NSString*)text heightWithFontSize:(CGFloat)fontSize width:(CGFloat)width lineSpacing:(CGFloat)lineSpacing {
    UILabel* label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, width, MAXFLOAT)];
    label.font = [UIFont systemFontOfSize:fontSize];
    label.numberOfLines = 0;
    [label setText:text lineSpacing:lineSpacing];
    [label sizeToFit];
    return label.height;
}

UITextView+Utils.m

+ (CGFloat)text:(NSString*)text heightWithFontSize:(CGFloat)fontSize width:(CGFloat)width lineSpacing:(CGFloat)lineSpacing {
    UITextView* textView = [[UITextView alloc] initWithFrame:CGRectMake(0, 0, width, MAXFLOAT)];
    textView.font = [UIFont systemFontOfSize:fontSize];
    [textView setText:text lineSpacing:lineSpacing];
    [textView sizeToFit];
    return textView.height;
}