Transparent Modal View on Navigation Controller

Question

I'm trying to create a transparent modal View on top of my navigation controller. Does anyone know if this is possible?

Answer 1

A modal view will cover the view it is pushed on top of as well as the navigation bar for your navigation controller. However, if you use the -presentModalViewController:animated: approach, then once the animation finishes the view just covered will actually disappear, which makes any transparency of your modal view pointless. (You can verify this by implementing the -viewWillDisappear: and -viewDidDisappear: methods in your root view controller).

You can add the modal view directly to the view hierarchy like so:

UIView *modalView =
    [[[UIView alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
modalView.opaque = NO;
modalView.backgroundColor =
    [[UIColor blackColor] colorWithAlphaComponent:0.5f];

UILabel *label = [[[UILabel alloc] init] autorelease];
label.text = @"Modal View";
label.textColor = [UIColor whiteColor];
label.backgroundColor = [UIColor clearColor];
label.opaque = NO;
[label sizeToFit];
[label setCenter:CGPointMake(modalView.frame.size.width / 2,
                                modalView.frame.size.height / 2)];
[modalView addSubview:label];

[self.view addSubview:modalView];

Adding the modalView as a subview to the root view like this will not actually cover the navigation bar, but it will cover the entire view below it. I tried playing around with the origin of the frame used to init the modalView, but negative values cause it to not display. The best method that I found to cover the entire screen besides the status bar is to add the modalView as a subview of the window itself:

TransparentModalViewAppDelegate *delegate = (TransparentModalViewAppDelegate *)[UIApplication sharedApplication].delegate;
[delegate.window addSubview:modalView];

Answer 2

The easiest way is to use modalPresentationStyle property of navigationController (but you'll have to make animation by yourself):

self.navigationController.modalPresentationStyle = UIModalPresentationCurrentContext;
[self presentModalViewController:modalViewController animated:NO];
modalViewController.view.alpha = 0;
[UIView animateWithDuration:0.5 animations:^{
    modalViewController.view.alpha = 1;
}];

Answer 3

I accomplish this most easily by setting up an "OverlayViewController" that sits above all other subviews of my window or root view. Set this up in your app delegate or root view controller, and make OverlayViewController a singleton so that it can be accessed from anywhere in your code or view controller hierarchy. You can then call methods to show modal views, show activity indicators, etc, whenever you need to, and they can potentially cover any tab bars or navigation controllers.

Sample code for root view controller:

- (void)viewDidLoad {
  OverlayViewController *o = [OverlayViewController sharedOverlayViewController];
  [self.view addSubview:o.view];
}

Sample code you might use to display your modal view:

[[OverlayViewController sharedOverlayViewController] presentModalViewController:myModalViewController animated:YES];

I haven't actually used -presentModalViewController:animated: with my OverlayViewController but I expect this would work just fine.

See also: What does your Objective-C singleton look like?

Answer 4

I had this same problem and in order to The solution is to add the modal view with addSubview: and animate the change in the view hierarchy with UIView’s animateWithDuration:delay:options:animations:completion:

I added a property and 2 methods to a subclass of UIViewController (FRRViewController) that includes other functionalities. I will be publishing the whole stuff on gitHub soon, but until then you can see the relevant code below. For more info, you can check my blog: How to display a transparent modal view controller.

#pragma mark - Transparent Modal View
-(void) presentTransparentModalViewController: (UIViewController *) aViewController 
                                     animated: (BOOL) isAnimated 
                                    withAlpha: (CGFloat) anAlpha{

    self.transparentModalViewController = aViewController;
    UIView *view = aViewController.view;

    view.opaque = NO;
    view.alpha = anAlpha;
    [view.subviews enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
        UIView *each = obj;
        each.opaque = NO;
        each.alpha = anAlpha;
    }];

    if (isAnimated) {
        //Animated
        CGRect mainrect = [[UIScreen mainScreen] bounds];
        CGRect newRect = CGRectMake(0, mainrect.size.height, mainrect.size.width, mainrect.size.height);


        [self.view addSubview:view];
        view.frame = newRect;

        [UIView animateWithDuration:0.8
                         animations:^{
                             view.frame = mainrect;
                         } completion:^(BOOL finished) {
                             //nop
                         }];

    }else{
        view.frame = [[UIScreen mainScreen] bounds];
        [self.view addSubview:view];
    }






}

-(void) dismissTransparentModalViewControllerAnimated:(BOOL) animated{

    if (animated) {
        CGRect mainrect = [[UIScreen mainScreen] bounds];
        CGRect newRect = CGRectMake(0, mainrect.size.height, mainrect.size.width, mainrect.size.height);
        [UIView animateWithDuration:0.8
                         animations:^{
                             self.transparentModalViewController.view.frame = newRect;
                         } completion:^(BOOL finished) {
                             [self.transparentModalViewController.view removeFromSuperview];
                             self.transparentModalViewController = nil;
                         }];
    }


}

Answer 5

Here's what I did to solve the problem - Google the details but this approach worked very well for me:

• Take a screenshot of the underlying view. https://devforums.apple.com/message/266836 - this leads to a ready-made method that returns a UIView for the current screen.
• Hand the screenshot to the modal view (I used a property)
• Present the modal view
• In the modal view controller's viewDidAppear, set the image as UIImageView at index 0. Adjust the vertical position of the image by the height of the status bar.
• In the modal view controller's viewWillDisappear, remove the image again

The effect is:

• The view animates in as any modal view does - the semi transparent parts of the modal view glide over the existing view
• As soon as the animation stops, the background is set to the screenshot - this makes it appear as if the old view is still underneath even though it isn't.
• As soon as the modal view's disappear animation starts, the image is removed. The OS meanwhile shows the old navigation view so the modal view transparently glides away and out of sight as you'd expect.

I tried animating in my own overlay view but it didn't work very well. I got a crash with no indication as to what has crashed. Rather than chase this down I did the bg view & Works really well.

Code in the modal view - I think you can figure out the rest, namely setting the property modalView.bgImage...

- (void)viewDidAppear:(BOOL)animated {
    // background
    // Get status bar frame dimensions
    CGRect statusBarRect = [[UIApplication sharedApplication] statusBarFrame];
    UIImageView *imageView = [[UIImageView alloc] initWithImage:self.bgImage];
    imageView.tag = 5;
    imageView.center = CGPointMake(imageView.center.x, imageView.center.y - statusBarRect.size.height);
    [self.view insertSubview:imageView atIndex:0];
}

- (void)viewWillDisappear:(BOOL)animated {
    [[self.view viewWithTag:5] removeFromSuperview];
}

Answer 6

This post about displaying a semi-transparent "Loading..." view might give a few pointers on how to proceed.

Answer 7

self.modalPresentationStyle = UIModalPresentationCurrentContext;
[self presentModalViewController:newview animated:YES];

and make sure you setup the modal view background to be transparent,

self.view.background = .... alpha:0.x;

Answer 8

if you set modalPresentationStyle for the modal view controller to:

viewController.modalPresentationStyle = 17;

The view in the background is not removed. (TWTweetComposeViewController use it).

I did not try to pass App Store review with this code though

Answer 9

Yeah, you have to add the view manually, and if you want to slide in from the bottom or whatever you have to do the animation yourself too.

I wrote a class to do this, and a semi-modal datepicker using that class as an example.

You can find documentation in this blog post, the code is on github

Answer 10

I've been researching this same issue for the past week. I tried all the various answers and examples found in Google and here on StackOverflow. None of them worked that well.

Being new to iOS programming, I wasn't aware of something called UIActionSheet. So if you're trying to accomplish this in order to show a modal overlay of buttons (such as a modal asking someone how they want to share something), just use UIActionSheet.

Here is a webpage that shows an example of how to do this.

Answer 11

I got this idea from https://gist.github.com/1279713

Prepare: In the modal view xib (or scene using storyboard), I setup the full-screen background UIImageView (hook it with the .h file and give it a property "backgroundImageView") with 0.3 alpha. And I set the view (UIView) background color as plain black.

Idea: Then in "viewDidLoad" of the modal view controller I capture the screenshot from the original status and set that image to the background UIImageView. Set the initial Y point to -480 and let it slide to Y point 0 using 0.4-second duration with EaseInOut animation option. When we dismiss the view controller, just do the reverse thing.

Code for the Modal View Controller Class

.h file:

@property (weak, nonatomic) IBOutlet UIImageView *backgroundImageView;
- (void) backgroundInitialize;
- (void) backgroundAnimateIn;
- (void) backgroundAnimateOut;

.m file:

- (void) backgroundInitialize{
    UIGraphicsBeginImageContextWithOptions(((UIViewController *)delegate).view.window.frame.size, YES, 0.0);
    [((UIViewController *)delegate).view.window.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage * screenshot = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    backgroundImageView.image=screenshot;
}
- (void) backgroundAnimateIn{
    CGRect backgroundImageViewRect = backgroundImageView.frame;
    CGRect backgroundImageViewRectTemp = backgroundImageViewRect;
    backgroundImageViewRectTemp.origin.y=-480;
    backgroundImageView.frame=backgroundImageViewRectTemp;

    [UIView animateWithDuration:0.4 delay:0.0 options:UIViewAnimationCurveEaseInOut animations:^{
        backgroundImageView.frame=backgroundImageViewRect;
    } completion:^(BOOL finished) {

    }];
}
- (void) backgroundAnimateOut{
    CGRect backgroundImageViewRect = backgroundImageView.frame;
    backgroundImageViewRect.origin.y-=480;

    [UIView animateWithDuration:0.4 delay:0.0 options:UIViewAnimationCurveEaseInOut animations:^{
        backgroundImageView.frame=backgroundImageViewRect;
    } completion:^(BOOL finished) {

    }];
}

In viewDidLoad, simply call:

[self backgroundInitialize];
[self backgroundAnimateIn];

In anywhere we dismiss the modal view controller, we call:

[self backgroundAnimateOut];

Please note that this will ALWAYS animate the background image. So if this modal view controller transition style (or the segue transition style) is not set to "Cover Vertical", you may not need to call the animation methods.

Answer 12

I finally accomplished this, for a navigation or tab bar interface, by combining an overlay view controller (see: pix0r's answer) that's hidden / un-hidden before hiding or showing a view controller based on this very good blog post.

Concerning the view controller, the tip is to make its background view the clearColor, then the semi-transparent overlay view is visible and whatever views are added as subviews in the view controller are in front and most importantly opaque.

Answer 13

I've created open soruce library MZFormSheetController to present modal form sheet on additional UIWindow. You can use it to present transparency modal view controller, even adjust the size of the presented view controller.

Answer 14

For iOS 8+ you can use UIModalPresentationOverCurrentContext presentation style for presented view controller to easy achieve desired behavior.

UIViewController *viewController = [[UIViewController alloc] init];
viewController.view.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.9f];
viewController.modalPresentationStyle = UIModalPresentationOverCurrentContext;
[self presentViewController:viewController animated:YES completion:nil];

If you also need to support iOS 7 - check this thread.