带有图像附件和 NSTextTab 的 NSAttributedString，文本未对齐

Question

我想要一个 UIlabel，左边是图片和标题，右边是带有项目符号的描述列表。

为此，我使用了 NSAttributedString，如下所示：

NSMutableParagraphStyle *pStyle = [[NSMutableParagraphStyle alloc] init];
pStyle.tabStops =
    @[ [[NSTextTab alloc] initWithTextAlignment:NSTextAlignmentLeft location:tabLocation options:[NSDictionary dictionary]] ];

NSMutableAttributedString *attString = [[NSMutableAttributedString alloc] init];
NSTextAttachment *textAttachment = [[NSTextAttachment alloc] init];
textAttachment.image = [UIImage imageNamed:@"test_image"];
textAttachment.bounds = CGRectMake(0, -3, 15, 15);//resize the image
attString = [NSAttributedString attributedStringWithAttachment:textAttachment].mutableCopy;
[attString appendAttributedString:[[NSAttributedString alloc]
                                      initWithString:[NSString stringWithFormat:@"title\t\u2022 %@",
                                                                                [@[ @"description1", @"description2" ]
                                                                                    componentsJoinedByString:@"\n\t\u2022 "]]
                                          attributes:@{NSParagraphStyleAttributeName : pStyle}]];
label.attributedText = attString;

我希望右边的列表是左对齐的，但事实并非如此，这是我得到的结果：

我希望列表像这样对齐：

Answer 1

如果我理解正确，请尝试这些代码：

UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 460, 460)];
label.numberOfLines = 0;
[self.view addSubview:label];

NSMutableParagraphStyle *pStyle = [[NSMutableParagraphStyle alloc] init];
pStyle.tabStops = @[ [[NSTextTab alloc] initWithTextAlignment:NSTextAlignmentLeft location:40 options:@{}] ];

NSTextAttachment *textAttachment = [[NSTextAttachment alloc] init];
textAttachment.image = [UIImage imageNamed:@"img"];
textAttachment.bounds = CGRectMake(0, -3, 30, 30);


NSString *string = [NSString stringWithFormat:@"title\n\r\u2022 %@", [@[ @"description1", @"description2" ] componentsJoinedByString:@"\n\r\u2022 "]];

NSMutableAttributedString *attributedString = [[NSMutableAttributedString attributedStringWithAttachment:textAttachment] mutableCopy];
[attributedString appendAttributedString:[[NSMutableAttributedString alloc] initWithString:string attributes:@{NSParagraphStyleAttributeName : pStyle}]];

label.attributedText = attributedString;

这是结果

更新

您只能使用 TextKit (NSTextLayoutManager) 并指定应该用于绘制文本的区域来实现此目的，或者使用简单的解决方案和 UIView 的子类。

这是视图的解决方案

ListView.h

@interface ListView : UIView

@property(nonatomic,strong) UIImage *image;
@property(nonatomic,strong) NSString *title;
@property(nonatomic,strong) NSArray *list;

@end

ListView.m

static const CGFloat ImageWidth = 13.f;

@interface ListView()
@property (nonatomic,weak) UIImageView *imageView;
@property (nonatomic,weak) UILabel *titleLabel;
@property (nonatomic,weak) UILabel *listLabel;
@end

@implementation ListView
- (instancetype)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    [self setup];
    return self;
}

- (instancetype)initWithCoder:(NSCoder *)aDecoder {
    self = [super initWithCoder:aDecoder];
    [self setup];
    return self;
}

- (void)awakeFromNib {
    [super awakeFromNib];
    [self setup];
}

- (void)setup {
    UIImageView *imageView = [[UIImageView alloc] init];
    imageView.translatesAutoresizingMaskIntoConstraints = NO;
    [self addSubview:imageView];
    self.imageView = imageView;

    UILabel *titleLabel = [[UILabel alloc] init];
    titleLabel.translatesAutoresizingMaskIntoConstraints = NO;
    titleLabel.numberOfLines = 0;
    [titleLabel setContentCompressionResistancePriority:UILayoutPriorityDefaultHigh forAxis:UILayoutConstraintAxisHorizontal];
    [titleLabel setContentHuggingPriority:UILayoutPriorityDefaultHigh forAxis:UILayoutConstraintAxisHorizontal];
    [self addSubview:titleLabel];
    self.titleLabel = titleLabel;

    UILabel *listLabel = [[UILabel alloc] init];
    listLabel.translatesAutoresizingMaskIntoConstraints = NO;
    listLabel.numberOfLines = 0;
    [listLabel setContentCompressionResistancePriority:UILayoutPriorityDefaultLow forAxis:UILayoutConstraintAxisHorizontal];
    [listLabel setContentHuggingPriority:UILayoutPriorityDefaultLow forAxis:UILayoutConstraintAxisHorizontal];
    [self addSubview:listLabel];
    self.listLabel = listLabel;

    NSDictionary *views = NSDictionaryOfVariableBindings(imageView,titleLabel,listLabel);
    NSDictionary *metrics = @{ @"ImageHeight" : @(ImageWidth) };

    [self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-0-[imageView(ImageHeight)]-0-[titleLabel]-0-[listLabel]-0-|" options:0 metrics:metrics views:views]];
    [self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-0-[imageView(ImageHeight)]" options:NSLayoutFormatAlignAllTop metrics:metrics views:views]];
    [self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-0-[titleLabel]" options:NSLayoutFormatAlignAllTop metrics:metrics views:views]];
    [self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-0-[listLabel]-0-|" options:NSLayoutFormatAlignAllTop metrics:metrics views:views]];
}

- (void)setImage:(UIImage *)image {
    _image = image;
    self.imageView.image = image;
    [self setNeedsLayout];
}

- (void)setTitle:(NSString *)title {
    _title = title;
    self.titleLabel.text = title;
    [self setNeedsLayout];
}

- (void)setList:(NSArray *)list {
    _list = list;

    NSMutableParagraphStyle *pStyle = [[NSMutableParagraphStyle alloc] init];
    pStyle.tabStops = @[ [[NSTextTab alloc] initWithTextAlignment:NSTextAlignmentLeft location:40 options:@{}] ];

    NSString *string = [NSString stringWithFormat:@"\u2022 %@", [list componentsJoinedByString:@"\n\u2022 "]];
    self.listLabel.attributedText = [[NSAttributedString alloc] initWithString:string attributes:@{NSParagraphStyleAttributeName : pStyle}];

    [self setNeedsLayout];
}

@end

Answer 2

问题出在 NSTextTab

中的 location 参数

根据描述，location 参数有助于从左边距定位文本。所以这就是我们需要的，只需替换下面的行

pStyle.tabStops =  @[ [[NSTextTab alloc] initWithTextAlignment:NSTextAlignmentLeft location:tabLocation options:[NSDictionary dictionary]] ];

和

pStyle.tabStops = @[[[NSTextTab alloc] initWithTextAlignment:NSTextAlignmentLeft location:[self getTextLocationFor:@"test"]  options:[NSDictionary dictionary]] ];

添加getTextLocationFor:方法计算位置如下

-(CGFloat)getTextLocationFor:(NSString *)inputStr{
     CGSize maximuminputStringWidth = CGSizeMake(FLT_MAX, 30);
     CGRect textRect = [inputStr boundingRectWithSize:maximuminputStringWidth
                                        options:NSStringDrawingUsesLineFragmentOrigin
                                     attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:15]}
                                        context:nil];
     UIImageView * testImage = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"close_red"]];//Change image name with yours

     return textRect.size.width + testImage.frame.size.width +2;
}

就这样我们准备好了运行你的项目现在一切都会好起来的。

结果：

带有图像附件和 NSTextTab 的 NSAttributedString，文本未对齐

NSAttributedString with image attachment and NSTextTab, text not aligned

ios

core-text

nstextattachment

nsparagraphstyle

nstexttab