iOS 8 Custom Keyboard: Changing the Height

This is my code on Xcode 6.0 GM. Both orientations are supported.

Update: Thanks to @SoftDesigner, we can eliminate the constraint conflict warning now.

Warning: XIB and storyboard are not tested. It’s been reported by some folks that this does NOT work with XIB.

KeyboardViewController.h

#import <UIKit/UIKit.h>

@interface KeyboardViewController : UIInputViewController

@property (nonatomic) CGFloat portraitHeight;
@property (nonatomic) CGFloat landscapeHeight;
@property (nonatomic) BOOL isLandscape;
@property (nonatomic) NSLayoutConstraint *heightConstraint;
@property (nonatomic) UIButton *nextKeyboardButton;

@end

KeyboardViewController.m

#import "KeyboardViewController.h"

@interface KeyboardViewController ()
@end

@implementation KeyboardViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Perform custom initialization work here
        self.portraitHeight = 256;
        self.landscapeHeight = 203;
    }
    return self;
}

- (void)updateViewConstraints {
    [super updateViewConstraints];
    // Add custom view sizing constraints here
    if (self.view.frame.size.width == 0 || self.view.frame.size.height == 0)
        return;

    [self.inputView removeConstraint:self.heightConstraint];
    CGSize screenSize = [[UIScreen mainScreen] bounds].size;
    CGFloat screenH = screenSize.height;
    CGFloat screenW = screenSize.width;
    BOOL isLandscape =  !(self.view.frame.size.width ==
                      (screenW*(screenW<screenH))+(screenH*(screenW>screenH)));
    NSLog(isLandscape ? @"Screen: Landscape" : @"Screen: Potriaint");
    self.isLandscape = isLandscape;
    if (isLandscape) {
        self.heightConstraint.constant = self.landscapeHeight;
        [self.inputView addConstraint:self.heightConstraint];
    } else {
        self.heightConstraint.constant = self.portraitHeight;
        [self.inputView addConstraint:self.heightConstraint];
    }
}

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
}

- (void)viewDidLoad {
    [super viewDidLoad];

    // Perform custom UI setup here
    self.nextKeyboardButton = [UIButton buttonWithType:UIButtonTypeSystem];

    [self.nextKeyboardButton setTitle:NSLocalizedString(@"Next Keyboard", @"Title for 'Next Keyboard' button") forState:UIControlStateNormal];
    [self.nextKeyboardButton sizeToFit];
    self.nextKeyboardButton.translatesAutoresizingMaskIntoConstraints = NO;

    [self.nextKeyboardButton addTarget:self action:@selector(advanceToNextInputMode) forControlEvents:UIControlEventTouchUpInside];

    [self.view addSubview:self.nextKeyboardButton];

    NSLayoutConstraint *nextKeyboardButtonLeftSideConstraint = [NSLayoutConstraint constraintWithItem:self.nextKeyboardButton attribute:NSLayoutAttributeLeft relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeLeft multiplier:1.0 constant:0.0];
    NSLayoutConstraint *nextKeyboardButtonBottomConstraint = [NSLayoutConstraint constraintWithItem:self.nextKeyboardButton attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeBottom multiplier:1.0 constant:0.0];
    [self.view addConstraints:@[nextKeyboardButtonLeftSideConstraint, nextKeyboardButtonBottomConstraint]];


    self.heightConstraint = [NSLayoutConstraint constraintWithItem:self.inputView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:0.0 constant:self.portraitHeight];

    self.heightConstraint.priority = UILayoutPriorityRequired - 1; // This will eliminate the constraint conflict warning.

}

- (void)textWillChange:(id<UITextInput>)textInput {
    // The app is about to change the document's contents. Perform any preparation here.
}

- (void)textDidChange:(id<UITextInput>)textInput {
}

@end

Swift 1.0 version:

class KeyboardViewController: UIInputViewController {

    @IBOutlet var nextKeyboardButton: UIButton!

    let portraitHeight:CGFloat = 256.0
    let landscapeHeight:CGFloat = 203.0
    var heightConstraint: NSLayoutConstraint?
    override func updateViewConstraints() {
        super.updateViewConstraints()
        // Add custom view sizing constraints here
        if (self.view.frame.size.width == 0 || self.view.frame.size.height == 0) {
            return
        }
        inputView.removeConstraint(heightConstraint!)
        let screenSize = UIScreen.mainScreen().bounds.size
        let screenH = screenSize.height;
        let screenW = screenSize.width;
        let isLandscape =  !(self.view.frame.size.width == screenW * ((screenW < screenH) ? 1 : 0) + screenH * ((screenW > screenH) ? 1 : 0))
        NSLog(isLandscape ? "Screen: Landscape" : "Screen: Potriaint");
        if (isLandscape) {
            heightConstraint!.constant = landscapeHeight;
            inputView.addConstraint(heightConstraint!)
        } else {
            heightConstraint!.constant = self.portraitHeight;
            inputView.addConstraint(heightConstraint!)
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        // Perform custom UI setup here
        self.nextKeyboardButton = UIButton.buttonWithType(.System) as UIButton

        self.nextKeyboardButton.setTitle(NSLocalizedString("Next Keyboard", comment: "Title for 'Next Keyboard' button"), forState: .Normal)
        self.nextKeyboardButton.sizeToFit()
    self.nextKeyboardButton.setTranslatesAutoresizingMaskIntoConstraints(false)

        self.nextKeyboardButton.addTarget(self, action: "advanceToNextInputMode", forControlEvents: .TouchUpInside)

        self.view.addSubview(self.nextKeyboardButton)

        var nextKeyboardButtonLeftSideConstraint = NSLayoutConstraint(item: self.nextKeyboardButton, attribute: .Left, relatedBy: .Equal, toItem: self.view, attribute: .Left, multiplier: 1.0, constant: 0.0)
        var nextKeyboardButtonBottomConstraint = NSLayoutConstraint(item: self.nextKeyboardButton, attribute: .Bottom, relatedBy: .Equal, toItem: self.view, attribute: .Bottom, multiplier: 1.0, constant: 0.0)
        self.view.addConstraints([nextKeyboardButtonLeftSideConstraint, nextKeyboardButtonBottomConstraint])

        heightConstraint = NSLayoutConstraint(item: self.inputView, attribute: NSLayoutAttribute.Height, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.NotAnAttribute, multiplier: 1.0, constant: portraitHeight)
        heightConstraint!.priority = 999.0
    }

    override func textWillChange(textInput: UITextInput) {
        // The app is about to change the document's contents. Perform any preparation here.
    }

    override func textDidChange(textInput: UITextInput) {
        // The app has just changed the document's contents, the document context has been updated.

        var textColor: UIColor
        var proxy = self.textDocumentProxy as UITextDocumentProxy
        if proxy.keyboardAppearance == UIKeyboardAppearance.Dark {
            textColor = UIColor.whiteColor()
        } else {
            textColor = UIColor.blackColor()
        }
        self.nextKeyboardButton.setTitleColor(textColor, forState: .Normal)
    }
}