Editing bounds of UIView when presenting hides key

问题:

I present a small "login" UIViewController as a UIModalPresentationFormSheet with custom bounds. In the viewWillLayoutSubviews method, I change the size of the view to (300,250). This has worked in iOS 5/6/7 but no longer works in 8.

When the view is presented and a UITextField is tapped, the app becomes unresponsive (not frozen, just not responding to touches). Almost as if the keyboard is presented but not appearing. Delegate methods ARE called correctly. If I remove the self.view.superview.bounds = CGRectMake(0, 0, 300, 250); from the viewWillLayoutSubviews method the keyboard works, but the view is now a full sized UIModalPresentationFormSheet style.

This only happens in iOS 8, so I can only assume its an issue with the way the keyboard is presented and the way I am masking/resizing the view, but I'm at a loss as to the solution.

Presenting ViewController -

UserLoginViewController *loginVC = [[UserLoginViewController alloc] initWithNibName:@"UserLoginViewController" bundle:nil];
loginVC.modalPresentationStyle = UIModalPresentationFormSheet;
loginVC.delegate = self;
[self presentViewController:loginVC animated:YES completion:nil];

Editing the view bounds -

- (void)viewWillLayoutSubviews {

    [super viewWillLayoutSubviews];
    self.view.superview.layer.cornerRadius  = 10.0;
    self.view.superview.layer.masksToBounds = YES;
    self.view.superview.bounds = CGRectMake(0, 0, 300, 250);
}

回答1:

In iOS8 You shouldn't change superview bounds in viewWillLayoutSubviews because it causes infinite loop.

EDIT: in iOS8 property preferredContentSize works well.

You should change your code in that way:

  UserLoginViewController *loginVC = [[UserLoginViewController alloc] initWithNibName:@"UserLoginViewController" bundle:nil];
    loginVC.modalPresentationStyle = UIModalPresentationFormSheet;
    loginVC.delegate = self;
    if(IS_IOS8)
    {
        loginVC.preferredContentSize = CGSizeMake(300, 250);
    }
    [self presentViewController:loginVC animated:YES completion:nil];

Editing the view bounds -

 - (void)viewWillLayoutSubviews{
    [super viewWillLayoutSubviews];

    self.view.superview.layer.cornerRadius  = 10.0;
    self.view.superview.layer.masksToBounds = YES;

    if(!IS_IOS8)
    {
        self.view.superview.bounds = CGRectMake(0, 0, 300, 250);
    }
}

Another way, which gives you more customization options is to use UIPresentationController and UIViewControllerTransitioningDelegate. Take a look at my code below.

Parent view controller:

 _aboutViewController = [[AboutViewController alloc] init];
        _aboutViewController.modalPresentationStyle = UIModalPresentationFormSheet;
        if(IS_IOS8)
        {
            if(aboutTransitioningDelegate == nil)
            {
                aboutTransitioningDelegate = [[AboutTransitioningDelegate alloc] init];
            }
            _aboutViewController.transitioningDelegate = aboutTransitioningDelegate;
            _aboutViewController.modalPresentationStyle = UIModalPresentationCustom;
        }
        [self presentViewController:_aboutViewController animated:YES completion:nil];

AboutViewController.m

#import "AboutViewController.h"

@interface AboutViewController ()

@end

@implementation AboutViewController

- (void)viewWillLayoutSubviews{
    [super viewWillLayoutSubviews];

    if(IS_IOS8)
    {
        return;
    }
    CGSize displaySize = CGSizeMake(320, 462);

    self.view.superview.bounds = CGRectMake(0, 0, displaySize.width, displaySize.height);
}

@end

AboutTransitioningDelegate.h:

@interface AboutTransitioningDelegate : NSObject <UIViewControllerTransitioningDelegate>

@end

AboutTransitioningDelegate.m:

#import "AboutTransitioningDelegate.h"
#import "AboutPresentationController.h"
@implementation AboutTransitioningDelegate

-(UIPresentationController *)presentationControllerForPresentedViewController:(UIViewController *)presented presentingViewController:(UIViewController *)presenting sourceViewController:(UIViewController *)source
{
    return [[AboutPresentationController alloc] initWithPresentedViewController:presented presentingViewController:presenting];
}
@end

AboutPresentationController.h

#import <UIKit/UIKit.h>

@interface AboutPresentationController : UIPresentationController

@end

AboutPresentationController.m

#import "AboutPresentationController.h"

@implementation AboutPresentationController


-(CGRect)frameOfPresentedViewInContainerView
{
    CGSize displaySize = CGSizeMake(320, 462);

    if([[Config sharedInstance] latestVersionFromAppstoreInstalled])
    {
        displaySize = CGSizeMake(320, 416);
    }

    CGRect  r =  CGRectZero;
    r.size = displaySize;
    r.origin.y = self.containerView.bounds.size.height/2 - displaySize.height/2;
    r.origin.x = self.containerView.bounds.size.width/2 - displaySize.width/2;
    return r;

}
-(void)containerViewWillLayoutSubviews
{
    [super containerViewWillLayoutSubviews];
    self.presentedView.frame = [self frameOfPresentedViewInContainerView];
}

@end

ProjectName-Prefix.pch

#define IS_IOS8 ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8)

回答2:

The simplest way to call containerViewWillLayoutSubviews() is to call:

containerView?.setNeedsLayout()