NSMutableParagraphStyle在台式机中使用uilabel(对齐异常)的自动高度

Question

在tableview重新加载后崩溃

这个问题只发生在iOS6上，iOS7很好。

例外说明：

NSTextAlignmentJustified和NSTextAlignmentNatural在绘制NSString (null)时是无效的对齐值(

0 CoreFoundation 0x00a702e exceptionPreprocess + 206

1 libobjc.A.dylib 0x03152e7e objc_exception_throw + 44

2 CoreFoundation 0x00aa6deb +NSException引发:格式：+ 139

_drawInRect:withFont:lineBreakMode:alignment:lineSpacing:includeEmoji:truncationRect：+ 88 3 UIKit 0x022ea8ec -NSString(UIStringDrawing)

drawInRect:withFont:lineBreakMode:alignment:lineSpacing:includeEmoji：+ 99 4 UIKit 0x022ea88f -NSString(UIStringDrawing)

drawInRect:withFont:lineBreakMode:alignment:lineSpacing：+ 91 5 UIKit 0x022e827 -NSString(UIStringDrawing)

_legacy_drawTextInRect:baselineCalculationOnly：+3433 6 UIKit 0x0241ce73 -UILabel

7 UIKit 0x0241cf76 -UILabel _drawTextInRect:baselineCalculationOnly：+ 160

8 UIKit 0x0241bcd9 -UILabel drawTextInRect：+ 548

9 UIKit 0x0241e098 -UILabel drawRect：+ 98

10 UIKit 0x0230fe6e (CALayerDelegate)拖曳层:inContext：+ 504

11 QuartzCore 0x0340ba3f -CALayer drawInContext：+ 128

12 QuartzCore 0x0340b96b _ZL16backing_callbackP9CGContextPv + 96

13 QuartzCore 0x0331d723 CABackingStoreUpdate_ + 2703

14 QuartzCore 0x0340b83c _ZN2CA5Layer8display_Ev + 1406

15 QuartzCore 0x0340b9ba -CALayer _display + 33

16 QuartzCore 0x0340b2b6 _ZN2CA5Layer7displayEv + 152

17 QuartzCore 0x0340b994 -CALayer显示器+ 33

_ZN2CA5Layer17display_if_neededEPNS_11TransactionE +328 18 QuartzCore 0x034000e2

_ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 38 19 QuartzCore 0x0340015c

_ZN2CA7Context18commit_transactionEPNS_11TransactionE +324 20 QuartzCore 0x0337e0bc

21 QuartzCore 0x0337f227 _ZN2CA11Transaction6commitEv + 395

_ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 96 22 QuartzCore 0x0337f8e2

__CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION + 30 23 CoreFoundation 0x00a6fafe

24 CoreFoundation 0x00a6fa3d __CFRunLoopDoObservers + 381

25 CoreFoundation 0x00a4d7c2 __CFRunLoopRun + 1106

26 CoreFoundation 0x00a4cf44 CFRunLoopRunSpecific + 276

27 CoreFoundation 0x00a4ce1b CFRunLoopRunInMode + 123

28 GraphicsServices 0x044bc7e3 GSEventRunModal + 88

29 GraphicsServices 0x044bc668 GSEventRun + 104

30 UIKit 0x022 UIKit+ 1211

31 DirectSeller 0x0000548 d main + 141

32 libdyld.dylib 0x03a2470d start +1)

我从未将对齐设置为"NSTextAlignmentJustified“或"NSTextAlignmentNatural".i无法理解。

自动高度代码：

dequeueReusableCellWithIdentifier:@"BasicCell"；DSBasicInfoPrototypeCell *cell = tableView NSString *titleText = data@"title"；

    NSMutableAttributedString *titleAttributedText = [[NSMutableAttributedString alloc] initWithString:titleText];
    NSMutableParagraphStyle *titleParagraphStyle = [[NSMutableParagraphStyle alloc] init];
    [titleParagraphStyle setLineSpacing:3.0f];
    titleParagraphStyle.alignment = NSTextAlignmentLeft;
    [titleAttributedText addAttribute:NSParagraphStyleAttributeName value:titleParagraphStyle range:NSMakeRange(0, titleText.length)];
    cell.titleLabel.attributedText = titleAttributedText;

    cell.titleLabel.preferredMaxLayoutWidth = 280;
    [cell.titleLabel setText:data[@"title"]];
    [cell.leftSubtitleLabel setText:data[@"source"]];
    [cell.rightSubtitleLabel setText:data[@"time"]];

    [cell setNeedsUpdateConstraints];
    [cell updateConstraintsIfNeeded];
    [cell.contentView setNeedsLayout];
    [cell.contentView layoutIfNeeded];

    return [cell.contentView systemLayoutSizeFittingSize:UILayoutFittingCompressedSize].height;

最后，为我糟糕的英语道歉。

Answer 1

通过为段落指定文本对齐(而不是让它默认)，我设法在iOS6上解决了这个问题：

paragraphStyle.alignment = NSTextAlignmentLeft;

希望它也对你有用。

Answer 2

我也有同样的问题，但我找不到根本原因。我认为这与在属性文本中使用ParagraphStyle有关。

我的解决办法是检查OS版本，如果小于7.0版本，我将使用标准文本而不是AttributedText。

这不是最好的解决方案，但它至少让我的应用停止在iOS6.1上崩溃，直到我找到更好的解决方案。

    NSString* text = @"Text\nText";

    NSString *ver   = [[UIDevice currentDevice] systemVersion];
    float ver_float = [ver floatValue];
    if (ver_float >= 7.0)
    {            
        NSMutableAttributedString* attributedText = [[NSMutableAttributedString alloc] initWithString:text];
        NSMutableParagraphStyle* paragraphStyle   = [[NSMutableParagraphStyle alloc] init];
        paragraphStyle.paragraphSpacing           = 6.0f;
        [attributedText addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, text.length)];

        [self.descLabel setAttributedText:attributedText];
    }
    else
    {            
        [self.descLabel setText:@"text"];
    }