Resize font size to fill UITextView?

Question

How would I set the font size of text in a UITextView such that it fills the entire UITextView? I\'d like the user to type in their text, then have the text fill the entire

Answer 1

Here is a conversion of dementiazz's and Matt Frear's answer to Swift 5. Put this function into viewDidLayoutSubviews, referencing the UITextView's who's font you want to dynamically resize.

func updateTextFont(textView: UITextView) {
    if (textView.text.isEmpty || textView.bounds.size.equalTo(CGSize.zero)) {
        return;
    }

    let textViewSize = textView.frame.size;
    let fixedWidth = textViewSize.width;
    let expectSize = textView.sizeThatFits(CGSize(width: fixedWidth, height: CGFloat(MAXFLOAT)))

    var expectFont = textView.font;
    if (expectSize.height > textViewSize.height) {
        while (textView.sizeThatFits(CGSize(width: fixedWidth, height: CGFloat(MAXFLOAT))).height > textViewSize.height) {
            expectFont = textView.font!.withSize(textView.font!.pointSize - 1)
            textView.font = expectFont
        }
    }
    else {
        while (textView.sizeThatFits(CGSize(width: fixedWidth, height: CGFloat(MAXFLOAT))).height < textViewSize.height) {
            expectFont = textView.font;
            textView.font = textView.font!.withSize(textView.font!.pointSize + 1)
        }
        textView.font = expectFont;
    }
}

Answer 2

Here is a solution for Swift 4 (based on Arie Litovsky answer), you can put this code into textViewDidChange(_ textView: UITextView) delegate method :

Scaling down the font :

    while (textView.contentSize.height > textView.frame.size.height) {
        guard let fontName = textView.font?.fontName, let fontSize = textView.font?.pointSize else {return}
        if fontSize < 12 {
            return
        }
        textView.font = UIFont(name: fontName, size: fontSize - 1)
        textView.layoutIfNeeded()
    }

And scaling up the font:

        while (textView.contentSize.height < textView.frame.size.height) {
        guard let fontName = textView.font?.fontName, let fontSize = textView.font?.pointSize else {return}
        if fontSize > 15 {
            return
        }
        textView.font = UIFont(name: fontName, size: fontSize + 1)
        textView.layoutIfNeeded()
    }

You can change the fontSize < 12 and fontSize > 15 to fit your needs in minimum and maximum font size.

Answer 3

This, in a category on UITextView, should do the trick. For why you need the fudgefactor, see this post

#define kMaxFieldHeight 9999 

-(BOOL)sizeFontToFit:(NSString*)aString minSize:(float)aMinFontSize maxSize:(float)aMaxFontSize 
{   
float fudgeFactor = 16.0;
float fontSize = aMaxFontSize;

self.font = [self.font fontWithSize:fontSize];

CGSize tallerSize = CGSizeMake(self.frame.size.width-fudgeFactor,kMaxFieldHeight);
CGSize stringSize = [aString sizeWithFont:self.font constrainedToSize:tallerSize lineBreakMode:UILineBreakModeWordWrap];

while (stringSize.height >= self.frame.size.height)
       {
       if (fontSize <= aMinFontSize) // it just won't fit
           return NO;

       fontSize -= 1.0;
       self.font = [self.font fontWithSize:fontSize];
       tallerSize = CGSizeMake(self.frame.size.width-fudgeFactor,kMaxFieldHeight);
       stringSize = [aString sizeWithFont:self.font constrainedToSize:tallerSize lineBreakMode:UILineBreakModeWordWrap];
       }

return YES; 
}

Answer 4

This property is only available on UITextFields. To do this in a UITextView, you'd have to constantly watch the text and manually adjust the font size as that changed.

Answer 5

An updated version of @Arie Litovsky's code. This works in iOS7 and later and stretches the font size both up and down so the text fits.

- (void) stretchFontToFit:(UITextView*)textView
{

    while( textView.contentSize.height < textView.frame.size.height )
    {
        textView.font = [textView.font fontWithSize:textView.font.pointSize +1];
        [textView layoutIfNeeded];
    }

    while( textView.contentSize.height > textView.frame.size.height )
    {
        textView.font = [textView.font fontWithSize:textView.font.pointSize -1];
        [textView layoutIfNeeded];
    }
}

Answer 6

I have converted dementiazz's & Matt Frear's answer to Swift 3:

func updateTextFont() {
        if (textView.text.isEmpty || textView.bounds.size.equalTo(CGSize.zero)) {
            return
        }

    let textViewSize = textView.frame.size
    let fixedWidth = textViewSize.width
    let expectSize = textView.sizeThatFits(CGSize(width: fixedWidth, height: CGFloat(MAXFLOAT)))

    var expectFont = textView.font
    if (expectSize.height > textViewSize.height) {
        while (textView.sizeThatFits(CGSize(width: fixedWidth, height: CGFloat(MAXFLOAT))).height > textViewSize.height) {
            expectFont = textView.font!.withSize(textView.font!.pointSize - 1)
            textView.font = expectFont
        }
    }
    else {
        while (textView.sizeThatFits(CGSize(width: fixedWidth, height: CGFloat(MAXFLOAT))).height < textViewSize.height) {
            expectFont = textView.font
            textView.font = textView.font!.withSize(textView.font!.pointSize + 1)
        }
        textView.font = expectFont
    }
}