UITextView的文字超越了界限

Question

我有一个不可滚动的UITextView,它的layoutManager maximumNumberOfLines设置为9,工作正常,但是,我似乎无法在NSLayoutManager中找到一个限制文本不超出UITextView框架的方法.

例如,在此屏幕截图中,光标位于第9行(第1行被剪切在屏幕截图的顶部,因此请忽略它).如果用户继续键入新字符,空格或点击返回键,则光标将继续在屏幕外显示,并且UITextView的字符串将继续变长.

由于外来字符大小不同,我不想限制UITextView的字符数.

我一直试图解决这个问题几个星期; 我非常感谢任何帮助.

CustomTextView.h

#import <UIKit/UIKit.h>

@interface CustomTextView : UITextView <NSLayoutManagerDelegate>

@end

CustomTextView.m

#import "CustomTextView.h"

@implementation CustomTextView

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self)
    {
        self.backgroundColor = [UIColor clearColor];
        self.font = [UIFont systemFontOfSize:21.0];
        self.dataDetectorTypes = UIDataDetectorTypeAll;
        self.layoutManager.delegate = self;
        self.tintColor = [UIColor companyBlue];
        [self setLinkTextAttributes:@{NSForegroundColorAttributeName:[UIColor companyBlue]}];
        self.scrollEnabled = NO;
        self.textContainerInset = UIEdgeInsetsMake(8.5, 0, 0, 0);
        self.textContainer.maximumNumberOfLines = 9;
    }
    return self;
}

- (CGFloat)layoutManager:(NSLayoutManager *)layoutManager lineSpacingAfterGlyphAtIndex:(NSUInteger)glyphIndex withProposedLineFragmentRect:(CGRect)rect
{
    return 4.9;
}

@end

更新,仍未解决

Answer 1

我认为这是一个更好的答案.每当调用shouldChangeTextInRange委托方法时,我们调用我们的didFit:string:range函数来查看结果文本高度是否超出视图高度.如果是,我们返回NO以防止发生变化.

-(BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {
    FLOG(@" called");

    // allow deletes
    if (text.length == 0)
        return YES;

    // Check if the text exceeds the size of the UITextView
    return [self doesFit:textView string:text range:range];

}
- (float)doesFit:(UITextView*)textView string:(NSString *)myString range:(NSRange) range;
{
    // Get the textView frame
    float viewHeight = textView.frame.size.height;
    float width = textView.textContainer.size.width;

    NSMutableAttributedString *atrs = [[NSMutableAttributedString alloc] initWithAttributedString: textView.textStorage];
    [atrs replaceCharactersInRange:range withString:myString];

    NSTextStorage *textStorage = [[NSTextStorage alloc] initWithAttributedString:atrs];
    NSTextContainer *textContainer = [[NSTextContainer alloc] initWithSize: CGSizeMake(width, FLT_MAX)];
    NSLayoutManager *layoutManager = [[NSLayoutManager alloc] init];

    [layoutManager addTextContainer:textContainer];
    [textStorage addLayoutManager:layoutManager];
    float textHeight = [layoutManager
            usedRectForTextContainer:textContainer].size.height;
    FLOG(@" viewHeight = %f", viewHeight);
    FLOG(@" textHeight = %f", textHeight);

    if (textHeight >= viewHeight - 1) {
        FLOG(@" textHeight >= viewHeight - 1");
        return NO;
    } else
        return YES;
}

编辑确定如果更改文本格式,还需要添加一些检查.在我的情况下,用户可以更改字体或使其变为粗体,更改段落样式等.所以现在任何这些更改也可能导致文本超出textView边框.

首先,您需要确保使用textViews undoManager注册这些更改.请参阅下面的示例(我只是复制整个attributedString,以便在调用undo时我可以将其放回去).

// This is in my UITextView subclass but could be anywhere

// This gets called to undo any formatting changes 
- (void)setMyAttributedString:(NSAttributedString*) atstr {
    self.attributedText = atstr;
    self.selectedRange = _undoSelection;
}
// Before we make any format changes save the attributed string with undoManager
// Also save the current selection (maybe should save this with undoManager as well using a custom object containing selection and attributedString)
- (void)formatText:(id)sender {
    //LOG(@"formatText: called");
    NSAttributedString *atstr = [[NSAttributedString alloc] initWithAttributedString:self.textStorage];
    [[self undoManager] registerUndoWithTarget:self
                               selector:@selector(setMyAttributedString:)
                                 object:atstr];
    // Remember selection
    _undoSelection = self.selectedRange;

   // Add text formatting attributes
   ...
   // Now tell the delegate that something changed
   [self.delegate textViewDidChange:self];
}

现在检查委托中的大小,如果不适合则撤消.

-(void)textViewDidChange:(UITextView *)textView {
    FLOG(@" called");
    if ([self isTooBig:textView]) {
        FLOG(@" text is too big so undo it!");
        @try {
            [[textView undoManager] undo];
        }
        @catch (NSException *exception) {
            FLOG(@" exception undoing things %@", exception);
        }
    }
}