为什么这会破坏UILabel adjustsFontSizeToFitWidth？

Question

iOS 7,Xcode 5

使用UILabel,此代码有效(自动调整文本以适应):

self.testLabel.numberOfLines=0;
self.testLabel.lineBreakMode=NSLineBreakByWordWrapping;
self.testLabel.adjustsFontSizeToFitWidth=YES;
self.testLabel.minimumScaleFactor=0.1;
self.testLabel.textAlignment=NSTextAlignmentCenter;
[self.testLabel.font fontWithSize:100.0];

但添加"setFont"行会导致它无法缩放字体以适应:

[self.testLabel setFont:[UIFont fontWithName:@"Helvetica Neue" size:62.0f]]; //THIS LINE CAUSES THE FONT SCALING TO FAIL
self.testLabel.numberOfLines=0;
self.testLabel.lineBreakMode=NSLineBreakByWordWrapping;
self.testLabel.adjustsFontSizeToFitWidth=YES;
self.testLabel.minimumScaleFactor=0.1;
self.testLabel.textAlignment=NSTextAlignmentCenter;
[self.testLabel.font fontWithSize:100.0];

有谁知道解决这个问题？

Answer 1

UILabel 如果设置,将调整多行文字的字体大小;

1. numberOfLines 到非零值.
2. lineBreakMode到NSLineBreakMode.ByTruncatingTail.

例如,

    _label.numberOfLines                =   2
    _label.lineBreakMode                =   NSLineBreakMode.ByTruncatingTail
    _label.adjustsFontSizeToFitWidth    =   true
    _label.minimumScaleFactor           =   0.4

经过测试并确认可以使用;

• Xcode 7.1.1
• 带有iOS 9.0.1的iPhone 6设备
• iOS 8.4的iPhone 4S模拟器
• iOS 8.1的iPhone 4S模拟器

Answer 2

好吧，看起来这基本上是一个错误，也许在 Xcode 6 中已修复。这在 iOS 7 中有效 - 我还没有在任何其他版本中测试过它。

同时，这是我用来缩小文本以适合我的 UILabel 的方法，具有多行和 AttributedString：

-(void)whAlertDisplayTheNotice:(UILabel*)inputlabel theNotice:(NSString*)theNotice {
    float maxFontSize=80.0;
    NSRange tmpRange=NSMakeRange(0,theNotice.length);
    NSMutableParagraphStyle *paragraph=[[NSMutableParagraphStyle alloc]init];
    paragraph.lineBreakMode=NSLineBreakByWordWrapping;
    paragraph.alignment=NSTextAlignmentCenter;
    paragraph.maximumLineHeight=maxFontSize;
    paragraph.lineSpacing=0;

    NSMutableAttributedString *attString=[[NSMutableAttributedString alloc] initWithString:theNotice];
    [attString addAttribute:NSParagraphStyleAttributeName
                      value:paragraph
                      range:tmpRange];
    [attString addAttribute:NSForegroundColorAttributeName
                      value:[UIColor blackColor]
                      range:tmpRange];

    CGSize constraintSize=CGSizeMake(inputlabel.frame.size.width, CGFLOAT_MAX);
    CGRect labelSize;
    for(short i=maxFontSize; i>8; i--){
        [attString addAttribute:NSFontAttributeName
                          value:[UIFont fontWithName:@"MV Boli" size:i]
                          range:tmpRange];
        inputlabel.attributedText=attString;
        labelSize=[inputlabel.attributedText boundingRectWithSize:constraintSize
                                                          options:(NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading)
                                                          context:nil];
        if(labelSize.size.height<inputlabel.frame.size.height){
            NSLog(@"fontsize is:%li",(long)i);
            break;
        }
    }
}