iOS 计算字符串显示宽高度

- (CGSize)getSizeWithFont:(UIFont *)font constrainedToSize:(CGSize)size{
CGSize resultSize = CGSizeZero;
if (self.length <= 0) {
return resultSize;
}
NSMutableParagraphStyle *style = [NSMutableParagraphStyle new];
style.lineBreakMode = NSLineBreakByWordWrapping;
resultSize = [self boundingRectWithSize:CGSizeMake(floor(size.width), floor(size.height))//用相对小的 width 去计算 height / 小 heigth 算 width
options:(NSStringDrawingUsesFontLeading | NSStringDrawingUsesLineFragmentOrigin)
attributes:@{NSFontAttributeName: font,
NSParagraphStyleAttributeName: style}
context:nil].size;
resultSize = CGSizeMake(floor(resultSize.width + 1), floor(resultSize.height + 1));//上面用的小 width（height） 来计算了，这里要 +1
return resultSize;
}

func getSizeWithFont(_ font:UIFont,constrainedToSize size:CGSize) -> CGSize{

if self.length == 0 { return CGSize.zero }

let style = NSMutableParagraphStyle.init()
style.lineBreakMode = .byWordWrapping

let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin)
let attributes = [NSFontAttributeName:font,NSParagraphStyleAttributeName:style]
let bound = CGSize.init(width: floor(size.width), height: floor(size.height))

let rect = self.boundingRect(with: bound, options: options, attributes: attributes, context: nil)
let _size = CGSize.init(width: floor(rect.width + 1), height: floor(rect.height + 1))

return _size
}