There is an answer posted at How do I size a UITextView to its content?
CGRect frame = _textView.frame;
frame.size.height = _textView.contentSize.height;
_textView.frame = frame;
or better(taking into account contentInset thanks to kpower's comment)
CGRect frame = _textView.frame;
UIEdgeInsets inset = textView.contentInset;
frame.size.height = _textView.contentSize.height + inset.top + inset.bottom;
_textView.frame = frame;
note: If you are going to reference a property of an object many times(e.g. frame or contentInset) it's better to assign it to a local variable so you don't trigger extra method calls(_textView.frame/[_textView frame] are method calls). If you are calling this code a lot(100000s of times) then this will be noticeably slower(a dozen or so method calls is insignificant).
However... if you want to do this in one line without extra variables it would be
_textView.frame = CGRectMake(_textView.frame.origin.x, _textView.frame.origin.y, _textView.frame.size.width, _textView.contentSize.height + _textView.contentInset.top + _textView.contentInset.bottom);
at the expense of 5 extra method calls.
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