NSTextAttachment 使用 textkit 时覆盖文本

Posted 2023-02-24

【中文标题】NSTextAttachment 使用 textkit 时覆盖文本

【英文标题】：NSTextAttachment cover the text when use textkit

【发布时间】：2015-06-07 15:10:28

【问题描述】：

我想在 UITextView 中插入图像，所以我使用 textkit 和 NSTextAttachment。但是当我插入图片时，图片显示在 UITextView 内容的上方，效果如下：

代码是这样的：

//
//  TextKitView.m
//  TextKit
//
//  Copyright (c) 2015 icell.com. All rights reserved.
//

#import "SNArticleView.h"

@interface SNArticleImageAttachment : NSTextAttachment

@end

@implementation SNArticleImageAttachment

- (CGRect)attachmentBoundsForTextContainer:(NSTextContainer *)textContainer proposedLineFragment:(CGRect)lineFrag glyphposition:(CGPoint)position characterIndex:(NSUInteger)charIndex 

    CGFloat attachmentWidth = CGRectGetWidth(lineFrag) - textContainer.lineFragmentPadding * 2;
    return CGRectMake(0, 0, attachmentWidth, attachmentWidth / self.image.size.width * self.image.size.height);




@end



@interface SNArticleView ()

@property (strong, nonatomic) NSTextStorage *textStorage;
@property (strong, nonatomic) UITextView *textView;

@end

@implementation SNArticleView

- (instancetype)initWithFrame:(CGRect)frame 
    self = [super initWithFrame:frame];
    if (self) 
        [self commonInit];
    
    return self;


- (void)commonInit 
    _textStorage = [[NSTextStorage alloc] init];

    NSLayoutManager *layoutManager = [[NSLayoutManager alloc] init];
    [_textStorage addLayoutManager:layoutManager];

    NSTextContainer *textContainer = [[NSTextContainer alloc] init];
    [layoutManager addTextContainer:textContainer];

    _textView = [[UITextView alloc] initWithFrame:self.bounds textContainer:textContainer];
    [_textView setAutoresizingMask:UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth];
    [_textView.textContainer setLineFragmentPadding:20];
    [self addSubview:_textView];


- (void)layoutSubviews 
    [super layoutSubviews];
    [self.textView setFrame:self.bounds];


- (void)setAttributedText:(NSAttributedString *)attributedText 
    _attributedText = [attributedText copy];
    [_textStorage insertAttributedString:_attributedText atIndex:0];


- (void)insertImage:(UIImage *)image atLocation:(NSUInteger)index; 
    NSMutableAttributedString *attributedTemp = [self.attributedText mutableCopy];

    SNArticleImageAttachment *attachment = [[SNArticleImageAttachment alloc] init];
    [attachment setImage:image];
    NSAttributedString *imageAttrStr = [NSAttributedString attributedStringWithAttachment:attachment];
    [attributedTemp insertAttributedString:imageAttrStr atIndex:_attributedText.length];

    [_textStorage replaceCharactersInRange:NSMakeRange(0, _attributedText.length) withAttributedString:attributedTemp];



@end

【参考方案1】：

最后，我自己找到了解决方案。因为我使用的NSAttributedString有一个段落样式的属性，而且我之前设置了MaximumLineHeight，所以影响了NSTextAttachment。