ObjC(Category of NSString):
- (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; }
Swift(Extension of NSString):
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( floor(size.width), height: floor(size.height)) let rect = self.boundingRect(with: bound, options: options, attributes: attributes, context: nil) let _size = CGSize.init( floor(rect.width + 1), height: floor(rect.height + 1)) return _size }