Uitextview Text Selection and Highlight Jumping in iOS 8

UITextView text selection and highlight jumping in iOS 8

I ended up solving my problem like this, and if someone else has a more elegant solution please let me know:

- (void)viewDidLoad {

    [super viewDidLoad];

    UIMenuItem *highlightMenuItem = [[UIMenuItem alloc] initWithTitle:@"Highlight" action:@selector(highlight)];
    [[UIMenuController sharedMenuController] setMenuItems:[NSArray arrayWithObject:highlightMenuItem]];

    float sysVer = [[[UIDevice currentDevice] systemVersion] floatValue];

    if (sysVer >= 8.0) {
        self.textView.layoutManager.allowsNonContiguousLayout = NO;
    } 
}

- (void)highlight {

    NSRange selectedTextRange = self.textView.selectedRange;

    [attributedString addAttribute:NSBackgroundColorAttributeName
                             value:[UIColor redColor]
                             range:selectedTextRange];

    float sysVer = [[[UIDevice currentDevice] systemVersion] floatValue];
    if (sysVer < 8.0) {
        // iOS 7 fix
        self.textView.scrollEnabled = NO;
        self.textView.attributedText = attributedString;
        self.textView.scrollEnabled = YES;
    } else {
        self.textView.attributedText = attributedString;
    }
}

Is it possible to change selection color in UITextView iOS?

Yes, you can change text selection color using tintColor property of UITextView.
Use this code to get the expected output.

self.textView.tintColor = .red

Also, You can do this from the storyboard, see the following image.

How to trigger an event when text is highlighted in swift

Assuming you are asking how to get an event when the selection changes in a UITextField, you need to add an observer to the "selectedTextRange" property of UITextField (from the UITextInput protocol).

Here is a little example view controller that listens to such events for a text field:

class MyVC: UIViewController {
    var textField: UITextField!

    @objc override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        if keyPath == "selectedTextRange" {
            if let tf = object as? UITextField {
                // This is our event and text field
                if let range = tf.selectedTextRange {
                    print("Updated selection = \(range)")
                }

                return
            }
        }

        // This isn't the event or the object we care about, pass it on
        super.observeValue(forKeyPath: keyPath, of: object, change: change, context: context)
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = .yellow

        textField = UITextField(frame: CGRect(x: 0, y: 0, width: 300, height: 44))
        textField.text = "Hello there. How are you?"

        // Options is empty because we don't care about the old range and we can get the new range from the text field
        textField.addObserver(self, forKeyPath: "selectedTextRange", options: [], context: nil)

        view.addSubview(textField)
    }

    deinit {
        textField.removeObserver(self, forKeyPath: "selectedTextRange")
    }
}

How to highlight text in a textView in Swift?

If you only need to highlight a single, contiguous block of text you can set the selection programmatically. Your examples show multiple discontinuous parts however. For that you are going to need to use an attributed string. There is no other system-provided highlighting function. (There might be a third party library that offers this though - you'll have to search.)

How to highlight or change color of text within iOS?

In iOS 6 you can do it, because iOS 6 now allows UITextView (as well as UILabel, UIButton etc.) to display styled text (NSAttributedString). You color the word with NSForegroundColorAttributeName and color its background with NSBackgroundColorAttributeName and presto, there's your highlight. There are several very good WWDC 2012 videos on this topic.

How to remove yellow selection highlight?

Found out that if I'm setting animate property to false it disappears.

pdfView.setCurrentSelection(wordSelection, animate: false)

UITextView starts at Bottom or Middle of the text

That did the trick for me!

Objective C:

[self.textView scrollRangeToVisible:NSMakeRange(0, 0)];

Swift:

self.textView.scrollRangeToVisible(NSMakeRange(0, 0))

Swift 2 (Alternate Solution)

Add this override method to your ViewController

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    textView.setContentOffset(CGPointZero, animated: false)
}

Swift 3 & 4 (syntax edit)

override func viewDidLayoutSubviews() {
  super.viewDidLayoutSubviews()

  textView.contentOffset = .zero
}

highlight a text in textview

It is only doable using CoreText, because it needs formatting attributes and NSAttributedString to display text with multiple font style and colors.

You may be interested in my OHAttributedLabel class that is a subclass of UILabel to render NSAttributedString (obviously it uses CoreText for this).

As setting the background color of a range of text is not directly possible/supported (no corresponding attribute in NSAttributedString), you may need to draw the yellow rectangles (before drawing the text) yourself, but I've done this in my class too to manage highlighted links (see drawActiveLinkHighlightForRect: method) so you may do a similar thing in your case.

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