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iOS-如何在UITEXTVIEW中找到可见的文本范围是什么？

发布于 2024-11-08 03:21:05 字数 8 浏览 0 评论 0原文

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丧 2024-11-15 03:21:05

I find another solution here.
It's a better way to solve this problem in my eyes.
https://stackoverflow.com/a/9283311/889892

Since UITextView is a subclass of UIScrollView, its bounds property reflects the visible part of its coordinate system. So something like this should work:

-(NSRange)visibleRangeOfTextView:(UITextView *)textView {
    CGRect bounds = textView.bounds;
    UITextPosition *start = [textView characterRangeAtPoint:bounds.origin].start;
    UITextPosition *end = [textView characterRangeAtPoint:CGPointMake(CGRectGetMaxX(bounds), CGRectGetMaxY(bounds))].end;
    return NSMakeRange([textView offsetFromPosition:textView.beginningOfDocument toPosition:start],
        [textView offsetFromPosition:start toPosition:end]);
}

This assumes a top-to-bottom, left-to-right text layout. If you want to make it work for other layout directions, you will have to work harder. :)

I find another solution here.
It's a better way to solve this problem in my eyes.
https://stackoverflow.com/a/9283311/889892

Since UITextView is a subclass of UIScrollView, its bounds property reflects the visible part of its coordinate system. So something like this should work:

-(NSRange)visibleRangeOfTextView:(UITextView *)textView {
    CGRect bounds = textView.bounds;
    UITextPosition *start = [textView characterRangeAtPoint:bounds.origin].start;
    UITextPosition *end = [textView characterRangeAtPoint:CGPointMake(CGRectGetMaxX(bounds), CGRectGetMaxY(bounds))].end;
    return NSMakeRange([textView offsetFromPosition:textView.beginningOfDocument toPosition:start],
        [textView offsetFromPosition:start toPosition:end]);
}

This assumes a top-to-bottom, left-to-right text layout. If you want to make it work for other layout directions, you will have to work harder. :)

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み零 2024-11-15 03:21:05

continue

The way i would do it is to compute all the sizes of each paragraph. With sizeWithFont:constrainedToSize:lineBreakMode:

you will then be able to work out which paragraph is visible, from the [textView contentOffset].

to scroll, dont use scrollRangeToVisible, just use setContentOffset: The CGPoint y parameter for this should either be the sum of all the height sizes to the next paragraph, or just add the textView.frame.size.height, if that is closer than the beginning of the next paragraph.

This make sense?

in answer to comment requst code bellow (untested):

  CGFloat paragraphOffset[MAX_PARAGRAPHS];

    CGSize constraint = CGSizeMake(widthOfTextView, 999999 /*arbitrarily large number*/);
    NSInteger paragraphNo = 0;
    CGFloat offset = 0;

    for (NSString* paragraph in paragraphs) {
        paragraphOffset[paragraphNo++] = offset;
        CGSize paragraphSize = [paragraph sizeWithFont:textView.font constrainedToSize:constraint lineBreakMode:UILineBreakModeWordWrap];
        offset += paragraphSize.height;
    }   

    // find visible paragraph
    NSInteger visibleParagraph = 0;
    while (paragraphOffset[visibleParagraph++] < textView.contentOffset.y);


    // scroll to paragraph 6
    [textView setContentOffset:CGPointMake(0, paragraphOffset[6]) animated:YES];

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じее 2024-11-15 03:21:05

如果你想要一个 Swift 解决方案，我使用这个：

Swift 2

public extension UITextView {
    public var visibleRange: NSRange? {
        if let start = closestPositionToPoint(contentOffset) {
            if let end = characterRangeAtPoint(CGPointMake(contentOffset.x + CGRectGetMaxX(bounds), contentOffset.y + CGRectGetMaxY(bounds)))?.end {
                return NSMakeRange(offsetFromPosition(beginningOfDocument, toPosition: start), offsetFromPosition(start, toPosition: end))
            }
        }
        return nil
    }
}

Swift 3

public extension UITextView {
    public var visibleRange: NSRange? {
        guard let start = closestPosition(to: contentOffset),
                  end = characterRange(at: CGPoint(x: contentOffset.x + bounds.maxX, 
                                                   y: contentOffset.y + bounds.maxY))?.end 
        else { return nil }
        return NSMakeRange(offset(from: beginningOfDocument, to: start), offset(from: start, to: end))
    }
}

If you want a Swift solution I use this:

Swift 2

public extension UITextView {
    public var visibleRange: NSRange? {
        if let start = closestPositionToPoint(contentOffset) {
            if let end = characterRangeAtPoint(CGPointMake(contentOffset.x + CGRectGetMaxX(bounds), contentOffset.y + CGRectGetMaxY(bounds)))?.end {
                return NSMakeRange(offsetFromPosition(beginningOfDocument, toPosition: start), offsetFromPosition(start, toPosition: end))
            }
        }
        return nil
    }
}

Swift 3

public extension UITextView {
    public var visibleRange: NSRange? {
        guard let start = closestPosition(to: contentOffset),
                  end = characterRange(at: CGPoint(x: contentOffset.x + bounds.maxX, 
                                                   y: contentOffset.y + bounds.maxY))?.end 
        else { return nil }
        return NSMakeRange(offset(from: beginningOfDocument, to: start), offset(from: start, to: end))
    }
}

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抱着落日 2024-11-15 03:21:05

基于“Noodle of Death”答案的 Swift 3.0/3.1 解决方案。

public extension UITextView {

    public var visibleRange: NSRange? {
        if let start = closestPosition(to: contentOffset) {
            if let end = characterRange(at: CGPoint(x: contentOffset.x + bounds.maxX, y: contentOffset.y + bounds.maxY))?.end {
                return NSMakeRange(offset(from: beginningOfDocument, to: start), offset(from: start, to: end))
            }
        }
        return nil
    }
}

Swift 3.0/3.1 solution based on "Noodle of Death" answer.

public extension UITextView {

    public var visibleRange: NSRange? {
        if let start = closestPosition(to: contentOffset) {
            if let end = characterRange(at: CGPoint(x: contentOffset.x + bounds.maxX, y: contentOffset.y + bounds.maxY))?.end {
                return NSMakeRange(offset(from: beginningOfDocument, to: start), offset(from: start, to: end))
            }
        }
        return nil
    }
}

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