計算具有不同字體類型的UILabel的大小

Question

我正在使用最低版本的iOS 7構建應用程序。在繪制單元格的方法中，我有這段代碼可以繪制具有不同UIFonts類型的UILabel 。

//Get Strings
NSString* author = [self getUserCreatedVideo:notf];
NSString* caption = [NSString stringWithFormat:@"\"%@\"", [notf objectForKey:@"title"]];
NSString* challenge = @"challenged you to reply to";
NSString* timeToReply = @"24h to reply";
NSString* myString = [NSString stringWithFormat:@"%@ %@ %@ %@", author, challenge, caption, timeToReply];

NSMutableAttributedString *str = [[NSMutableAttributedString alloc] initWithString:myString];
UIColor* greenColor = [UIColor colorWithRed:102.0/255.0 green:204.0/255.0 blue:153.0/255.0 alpha:1];

//Author
[str addAttribute:NSForegroundColorAttributeName value:[UIColor darkGrayColor] range:NSMakeRange(0,author.length)];
[str addAttribute:NSFontAttributeName value: [UIFont fontWithName:@"Helvetica" size:17.0] range:NSMakeRange(0,author.length)];
//Challenge
[str addAttribute:NSForegroundColorAttributeName value:[UIColor lightGrayColor] range:NSMakeRange(author.length+1,challenge.length)];
[str addAttribute:NSFontAttributeName value: [UIFont fontWithName:@"Helvetica" size:13.0] range:NSMakeRange(author.length+1,challenge.length)];
//Caption
[str addAttribute:NSForegroundColorAttributeName value:[UIColor darkGrayColor] range:NSMakeRange(author.length+1+challenge.length+1,caption.length)];
[str addAttribute:NSFontAttributeName value: [UIFont fontWithName:@"Helvetica" size:14.0] range:NSMakeRange(author.length+1+challenge.length+1,caption.length)];
//Time To Reply
[str addAttribute:NSForegroundColorAttributeName value:greenColor range:NSMakeRange(author.length+1+challenge.length+1+caption.length+1,timeToReply.length)];
[str addAttribute:NSFontAttributeName value: [UIFont fontWithName:@"Helvetica" size:14.0] range:NSMakeRange(author.length+1+challenge.length+1+caption.length+1,4)];

cell.subtext.attributedText = str;

現在，我想計算UILabel文本大小，以便可以在cell.subtext下面繪制20px的UILabel 。 我怎樣才能做到這一點？

Answer 1

因此，基本上，您希望在知道文本寬度時計算文本的高度。

CGRect rect = [str boundingRectWithSize:CGSizeMake(cellWidth, MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin context:nil];

以所需的方式使用生成的rect.size。