在Objective-c中没有获得正确的UILabel高度

NSString *text = @"Your text goes here";
UIFont *font = [UIFont systemFontOfSize:17.0]; // 设置UILabel的字体大小
CGSize constraintSize = CGSizeMake(labelWidth, MAXFLOAT); // 设置UILabel的宽度，高度设置为MAXFLOAT
CGSize labelSize = [text boundingRectWithSize:constraintSize options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:font} context:nil].size;
CGFloat labelHeight = ceilf(labelSize.height); // 向上取整得到正确的UILabel高度

CGRect labelFrame = label.frame;
labelFrame.size.height = labelHeight;
label.frame = labelFrame;