How to calculate TextView height base on text

Question

I am using the code below for calculate the height of text, then set this height for UILabel and UITextView

CGSize targetSize = CGS         


        

Answer 1

Most of the answers here are hints into the right direction :-)

So, just to sum it all up...

UITextView uses a NSTextContainer (inside a private API _UITextContainerView) to do the real layout work. This NSTextContainer(View) may have insets to the surrounding UITextView, which are set by UITextView's textContainerInset property. The defaults for this insets seem to be:

• top: 8
• left: 0
• bottom: 8
• right: 0

The NSTextContainer itself may have additional left and right insets for the text itself. These insets are set in NSTextContainer's lineFragmentPadding property.

• The default for this is 5.0.

As a result, when calculating the optimum frame size for a UITextView based on the boundingRect for some text inside that UITextView, we have to take all these insets into account:

CGSize reservedSpace = CGSizeMake((textView.textContainerInset.left + (2.0 * textView.textContainer.lineFragmentPadding) + textView.textContainerInset.right),
                                  (textView.textContainerInset.top + textView.textContainerInset.bottom));
CGSize targetSize = CGSizeMake((300.0 - reservedSpace.width), CGFLOAT_MAX);
NSString* message = @"The Internet connection appears to be offline.";

NSStringDrawingContext* context = [[NSStringDrawingContext alloc] init];
CGSize boundingBox = [message boundingRectWithSize:targetSize
                                              options:NSStringDrawingUsesLineFragmentOrigin
                                           attributes:@{NSFontAttributeName:FontOpenSanWithSize(14)}
                                              context:context].size;

CGSize size = CGSizeMake(ceil(boundingBox.width),
                         (ceil(boundingBox.height) + reservedSpace.height));

Good luck :-)