计算出UIlabel显示文字的行数

参考文章

- (NSInteger)needLinesWithWidth:(CGFloat)width;{
    UILabel *label = [[UILabel alloc] init];
    label.font = self.font;
    NSString *text = self.text;
    NSInteger sum = 0;
    if (text.length != 0) {
        NSArray *splitTexts = [text componentsSeparatedByCharactersInSet:[NSCharacterSet newlineCharacterSet]];
        for (NSString *stext in splitTexts) {
            label.text = stext;
            CGSize textSize = [label systemLayoutSizeFittingSize:CGSizeZero];
            NSInteger lines = ceilf(textSize.width / width);
            lines = lines == 0 ? 1 : lines;
            sum += lines;
        }
    }
    return sum;
}