由于未捕获异常“CALayerInvalidGeometry”而终止应用程序，原因：“CALayer bounds包含NaN：[0 nan; 280 524]

问题描述

我正在开发一个书应用程序，用户可以在TextView上更改字体大小。

I am developing a book app where users can change the font size on the TextView.

当用户更改字体大小时，应用程序保存当前文本位置不在用户更改字体大小后更改。

when users change the font size, the app save the current text position not to change that after users did changing font size.

在大多数情况下它可以正常工作，但有时，当用户更改字体大小时，应用程序会收到这种错误，

It works fine in most cases, but sometimes, when users change the font size, the app gets this kind of error, and I still can't tell how to fix this.

也无法重现此问题100％，因为这个问题偶尔会发生。

I also can't reproduce this issue 100% since this issue happens occasionally.

这是代码。有人有想法来解决这个问题吗？提前感谢。

This is the code. Does anybody have an idea to fix this? Thanks in advance.

- (UITextRange *)getCurrentTextRange:(UITextView *)textView {

    CGRect bounds               = textView.bounds;
    UITextPosition *start       = [textView characterRangeAtPoint:bounds.origin].start;
    UITextPosition *end         = [textView positionFromPosition:start offset:1];
    UITextRange *textRange      = [textView textRangeFromPosition:start toPosition:end];

    return textRange;
}

- (void)changeFontSize:(UIButton*)button {

    UITextRange *textRange  = [self getCurrentTextRange:_textView];
    int fontSize            = [[NSUserDefaults standardUserDefaults] integerForKey:@"fontSize"];

    //button.tag == 1 => decreaseFontSize
    if (button.tag == 1) {

        //set a minimum size
        if (fontSize <= [LSUniversalManager getFontSizeForMinimum]) {
            return;
        }

        fontSize--;

    //button.tag == 2 => increaseFontSize
    } else if (button.tag == 2) {
        fontSize++;
    }

    _textView.font      = [UIFont systemFontOfSize:fontSize];
    [[NSUserDefaults standardUserDefaults] setInteger:fontSize forKey:@"fontSize"];

    //avoid shifting the scroll position after changing font size
    CGRect rect = [_textView firstRectForRange:textRange];
    [_textView setContentOffset:CGPointMake(0, rect.origin.y)];
}

推荐答案

你得到一个无效的输出，导致 rect 有值 NaN （一个特殊的浮动值意味着不是有效浮点数，最常见的是由零除）。是否可能已将无效或无意义的 UITextRange 传递给 -firstRectForRange ？如果 UITextPosition * start 引用文本中的最后一个字符，然后创建另一个超出结束一个字符的文本位置，会发生什么？

Somewhere along the line here, you are getting an invalid output that is causing rect to have the value NaN (a special float value meaning "not a valid float number", most commonly caused by division by zero). Is it possible that you have passed an invalid or nonsensical UITextRange to -firstRectForRange? What happens if UITextPosition *start references the last character in the text, when you then create another text position that is one character past the end?

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