根据文字返回Label高度

NSString分类

@implementation NSString (stringSize)

//计算文字显示的所需要的size

-(CGSize)sizeWithFont:(UIFont *)font Size:(CGSize)size{

NSDictionary *attributes = @{NSFontAttributeName: font};

return [self boundingRectWithSize:size options:NSStringDrawingUsesLineFragmentOrigin attributes:attributes context:nil].size;

}

@end

CGFloat textHeight = [comment.text sizeWithFont:[UIFont systemFontOfSize:17] Size:CGSizeMake(With, MAXFLOAT)].height;