Implement custom animation to present modal view from specified view on iPad

Question

On the iPad we get much more room to work with, so presenting full screen modal views is not ideal.

I know how to present modal views in the new formSheet and a close approach can be found on this question: iPad iTunes Animation

The problem is that you cannot choose where the animation will come from, so it just defaults and appears from the center, I want to customize it so that it appears from a specific location.

The best example I can find for this animation can be seen on the first few seconds of this video

If anyone can point me on the right direction using code, tutorials or documentation I would greatly appreciate it!

Update:

After some investigation I have found that this can be done using layers and Core Animation for the first part; and then animate it a formSheet modal view but I still dont quite understand how to achieve it, hopefully you guys can help!

Answer 1

What I did was creating a new category for UIViewController as follows

UIViewController+ShowModalFromView.h

#import <Foundation/Foundation.h>
#import <QuartzCore/QuartzCore.h>

@interface UIViewController (ShowModalFromView)

- (void)presentModalViewController:(UIViewController *)modalViewController fromView:(UIView *)view;

@end

UIViewController+ShowModalFromView.m

#import "UIViewController+ShowModalFromView.h"

@implementation UIViewController (ShowModalFromView)

- (void)presentModalViewController:(UIViewController *)modalViewController fromView:(UIView *)view
{
    modalViewController.modalPresentationStyle = UIModalPresentationFormSheet;

    // Add the modal viewController but don't animate it. We will handle the animation manually
    [self presentModalViewController:modalViewController animated:NO];

    // Remove the shadow. It causes weird artifacts while animating the view.
    CGColorRef originalShadowColor = modalViewController.view.superview.layer.shadowColor;
    modalViewController.view.superview.layer.shadowColor = [[UIColor clearColor] CGColor];

    // Save the original size of the viewController's view    
    CGRect originalFrame = modalViewController.view.superview.frame;

    // Set the frame to the one of the view we want to animate from
    modalViewController.view.superview.frame = view.frame;

    // Begin animation
    [UIView animateWithDuration:1.0f
                     animations:^{
                         // Set the original frame back
                         modalViewController.view.superview.frame = originalFrame;
                     }
                     completion:^(BOOL finished) {
                         // Set the original shadow color back after the animation has finished
                         modalViewController.view.superview.layer.shadowColor = originalShadowColor;
                     }];
}

@end

It's pretty straight forward. Please let me know if this helps you.

UPDATE

I've updated the answer to use animation blocks instead of [UIView beginAnimations:nil context:nil]; / [UIView commitAnimations] pair.