/*

     File: ViewController.m

 Abstract: View controller that adds a keyboard accessory to a text view.

  Version: 1.5

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 */

#import "ViewController.h"

@interface ViewController () <UITextViewDelegate>

@property (nonatomic, weak) IBOutlet UITextView *textView;

@property (nonatomic, weak) IBOutlet UIView *accessoryView; // view placed on top of keyboard

@property (nonatomic, weak) IBOutlet UIBarButtonItem *editButton;

@property (nonatomic, weak) IBOutlet UIBarButtonItem *doneButton;

// the height constraint we want to change when the keyboard shows/hides

@property (weak, nonatomic) IBOutlet NSLayoutConstraint *constraintToAdjust;

@end

#pragma mark -

@implementation ViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    // set the right bar button item initially to "Edit" state

    self.navigationItem.rightBarButtonItem = self.editButton;

}

- (void)viewDidAppear:(BOOL)animated {

    // observe keyboard hide and show notifications to resize the text view appropriately

    [[NSNotificationCenter defaultCenter] addObserver:self

                                             selector:@selector(keyboardWillShow:)

                                                 name:UIKeyboardWillShowNotification

                                               object:nil];

    [[NSNotificationCenter defaultCenter] addObserver:self

                                             selector:@selector(keyboardWillHide:)

                                                 name:UIKeyboardWillHideNotification

                                               object:nil];

    // start editing the UITextView (makes the keyboard appear when the application launches)

    [self editAction:self];

}

- (void)viewDidDisappear:(BOOL)animated {

    [[NSNotificationCenter defaultCenter] removeObserver:self

                                                    name:UIKeyboardWillChangeFrameNotification

                                                  object:nil];

    [[NSNotificationCenter defaultCenter] removeObserver:self

                                                    name:UIKeyboardWillHideNotification

                                                  object:nil];

}

- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation {

    [self adjustSelection:self.textView];

}

#pragma mark - Actions

- (IBAction)doneAction:(id)sender {

    // user tapped the Done button, release first responder on the text view

    [self.textView resignFirstResponder];

}

- (IBAction)editAction:(id)sender {

    // user tapped the Edit button, make the text view first responder

    [self.textView becomeFirstResponder];

}

#pragma mark - UITextViewDelegate

- (BOOL)textViewShouldBeginEditing:(UITextView *)aTextView {

    // note: you can create the accessory view programmatically (in code), or from the storyboard

    if (self.textView.inputAccessoryView == nil) {

        self.textView.inputAccessoryView = self.accessoryView;  // use what's in the storyboard

    }

    self.navigationItem.rightBarButtonItem = self.doneButton;

    return YES;

}

- (BOOL)textViewShouldEndEditing:(UITextView *)aTextView {

    [aTextView resignFirstResponder];

    self.navigationItem.rightBarButtonItem = self.editButton;

    return YES;

}

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

    // workaround to UITextView bug, text at the very bottom is slightly cropped by the keyboard

    if ([textView respondsToSelector:@selector(textContainerInset)]) {

        [textView layoutIfNeeded];

        CGRect caretRect = [textView caretRectForPosition:textView.selectedTextRange.end];

        caretRect.size.height += textView.textContainerInset.bottom;

        [textView scrollRectToVisible:caretRect animated:NO];

    }

}

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

    [self adjustSelection:textView];

}

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

    [self adjustSelection:textView];

}

#pragma mark - Responding to keyboard events

- (void)adjustTextViewByKeyboardState:(BOOL)showKeyboard keyboardInfo:(NSDictionary *)info {

    /*

     Reduce the size of the text view so that it's not obscured by the keyboard.

     Animate the resize so that it's in sync with the appearance of the keyboard.

     */

    // transform the UIViewAnimationCurve to a UIViewAnimationOptions mask

    UIViewAnimationCurve animationCurve = [info[UIKeyboardAnimationCurveUserInfoKey] unsignedIntegerValue];

    UIViewAnimationOptions animationOptions = UIViewAnimationOptionBeginFromCurrentState;

    if (animationCurve == UIViewAnimationCurveEaseIn) {

        animationOptions |= UIViewAnimationOptionCurveEaseIn;

    }

    else if (animationCurve == UIViewAnimationCurveEaseInOut) {

        animationOptions |= UIViewAnimationOptionCurveEaseInOut;

    }

    else if (animationCurve == UIViewAnimationCurveEaseOut) {

        animationOptions |= UIViewAnimationOptionCurveEaseOut;

    }

    else if (animationCurve == UIViewAnimationCurveLinear) {

        animationOptions |= UIViewAnimationOptionCurveLinear;

    }

    [self.textView setNeedsUpdateConstraints];

    if (showKeyboard) {

        UIDeviceOrientation orientation = self.interfaceOrientation;

        BOOL isPortrait = UIDeviceOrientationIsPortrait(orientation);

        NSValue *keyboardFrameVal = [info objectForKey:UIKeyboardFrameEndUserInfoKey];

        CGRect keyboardFrame = [keyboardFrameVal CGRectValue];

        CGFloat height = isPortrait ? keyboardFrame.size.height : keyboardFrame.size.width;

        // adjust the constraint constant to include the keyboard's height

        self.constraintToAdjust.constant += height;

    }

    else {

        self.constraintToAdjust.constant = 0;

    }

    NSTimeInterval animationDuration = [[info objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];

    [UIView animateWithDuration:animationDuration delay:0 options:animationOptions animations:^{

        [self.view layoutIfNeeded];

    } completion:nil];

    // now that the frame has changed, move to the selection or point of edit

    NSRange selectedRange = self.textView.selectedRange;

    [self.textView scrollRangeToVisible:selectedRange];

}

- (void)keyboardWillShow:(NSNotification *)notification {

    /*

     Reduce the size of the text view so that it's not obscured by the keyboard.

     Animate the resize so that it's in sync with the appearance of the keyboard.

     */

    NSDictionary *userInfo = [notification userInfo];

    [self adjustTextViewByKeyboardState:YES keyboardInfo:userInfo];

}

- (void)keyboardWillHide:(NSNotification *)notification {

    /*

     Restore the size of the text view (fill self's view).

     Animate the resize so that it's in sync with the disappearance of the keyboard.

     */

    NSDictionary *userInfo = [notification userInfo];

    [self adjustTextViewByKeyboardState:NO keyboardInfo:userInfo];

}

#pragma mark - Accessory view action

- (IBAction)tappedMe:(id)sender {

    // when the accessory view button is tapped, add a suitable string to the text view

    NSMutableString *text = [self.textView.text mutableCopy];

    NSRange selectedRange = self.textView.selectedRange;

    [text replaceCharactersInRange:selectedRange withString:@"\nYou tapped me."];

    self.textView.text = text;

    [self adjustSelection:sender];

}

@end