Is it possible to set a property application-wide to double the speed of transitions within an iOS app?
Application-wide?
Try setting the speed property on the backing layer for your view controllers' content views. speed=2 would be double-speed. You could probably set this in the viewDidLoad method for all your view controllers.
You might also be able to create a custom subclass of UIWindow, and have that window object set the speed property on it's view layer to 2.0 in a bottleneck method like makeKeyWindow. You'd need to make all your app's UIWindow objects use your custom class. I'd have to do some digging to figure out how to do that.
##Edit:
Or, better idea, set self.window.layer.speed = 2.0 in your app delegate after creating the window, as suggested by #Costique in the comment below.
Note that this approach will speed up ALL animations, not just transitions and segues. If you only want to speed up segues you would have to figure out how to target just those animations. I'd have to think about that.
Apple does not have a simple way to change that since it would make transitions too heterogenous amongst different apps. You could double the layer's speed, but that would mess up the timing on the rest of your animations. The best way is to implement your own transition using a category on UIViewControler.
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
This can easily be changed to use whatever animated transition you want. Hope this helps!
Related
In facebook'a new app, Pages, when you swipe down the menu appears at the top. The animation I am trying to do is the animation when you tap the settings button which is when each cell moves to the left one at a time, but very smoothly. How can I achieve such an animation without using Facebook's pop engine in Objective C ?
Bear in mind that each cell is probably a custom subclass of UIView (i.e. not UITableViewCell or other apple class) so you will have to design your UI carefully.
The animation, however, is easily achievable using the UIView class. Apple's documentation is a good place to start to learn about animation.
What you want is something like:
NSTimeInterval delay = 0.2;
for (UIView *myView in myViewArray) {
[UIView animateWithDuration:0.5 delay:delay options:UIViewAnimationOptionCurveEaseInOut animations:^{
/*
* This is where you set the properties you want to animate.
* If you're using AutoLayout (i.e. NSLayoutConstraint) you need to set the constant property of the relevant constraint, not the view's frame property.
*/
} completion:nil];
delay += 0.2;
}
This will provide you with animations that occur one after the other (0.2 seconds apart).
I want to use Storyboards to design content for a slider, and it seems like an easy way to design offscreen content is to use a childViewController. So I've done this
myViewController = [[UIStoryboard storyboardWithName:#"ipad" bundle:NULL] instantiateViewControllerWithIdentifier:#"keyPadOffScreen"];
[self addChildViewController:myViewController];
[myViewController didMoveToParentViewController:self];
newView = myViewController.view;
[self.view addSubview:newView];
And that adds the entire view controller over top of my root view. The problem is, I only want one of the subviews to show up, not the whole view. I can handle the animation, as long as I know how to add the root view. I tried this to just add the subview (sliderView is the name of the subview I want) instead of the whole view, but that did nothing
newView = myViewController.sliderView;
[self.view addSubview:newView];
Should I be using a different strategy?
EDIT: this DOES work, but it seems silly - setting the views size to just be the size of the subview.
newView.frame = CGRectMake(newView.frame.origin.x, newView.frame.origin.y, newView.frame.size.width, **myViewController.sliderView.frame.size.height**);
It does seem a bit overkill for just a view. Once you start doing a lot of custom view/animation/transition stuff it's often easier to implement in code, or at least it is for me since I've been doing it that way for a long time.
But maybe you want to stick with Storyboards. I respect that. And if you have a few developers working on this then it's important to keep some uniformity to how you set up your UI.
Instead of keeping it in a separate view controller and adding it when you need it to animate on-screen, simply add it to your existing view controller and either set it to hidden, or set it's alpha to 0.0 in IB. Then your animation can undo that and make it visible.
you can use custom segue here, for instance:
#implementation FRPresentEnteringPopupSegue
- (void)perform
{
FirstVC *toVC = self.destinationViewController;
SecondNavigationController *fromVC = self.sourceViewController;
toVC.view.frame = CGRectMake(0.0, 0.0, 300.0, 135.0);
toVC.view.center = CGPointMake(fromVC.view.bounds.size.width/2, fromVC.view.bounds.size.height + toVC.view.bounds.size.height/2);
[fromVC.view addSubview:toVC.view];
[toVC viewWillAppear:YES];
[UIView animateWithDuration:0.5
delay:0.0
usingSpringWithDamping:0.7
initialSpringVelocity:0.5
options:UIViewAnimationOptionBeginFromCurrentState
animations:^{
toVC.view.center = CGPointMake(fromVC.view.bounds.size.width/2, fromVC.view.bounds.size.height/2);
}completion:^(BOOL finished) {
[toVC viewDidAppear:YES];
}];
}
#end
make your UIStoryboardSegue subclass
override - (void)perform method with your custom view appearance code
use segue usual way
I need to change the width of a subview depending on, say, available disk space. So I have a selector that's called upon the view controller's viewWillLayoutSubviews as such:
CGRect rect = self.usageView.bounds;
rect.size.width = self.someCalculatedwidth;
[self.usageView setFrame:rect];
[self.usageView setNeedsDisplay];
Really, I just want to change the width of the subview. It works if the view controller is the initial controller; however, if it is transitioned from, say, a Push Segue it stopped working. What happens is I'd see my desired width rendered for moment but then it gets changed to the original width as per its blueprint on the Storyboard.
The behavior feels like the iOS caches the original (storyboard) view in a block during the push segue animation, and upon completion it executes the block which doesn't have my calculations above; thereby overridden the desired view. Any idea?
There are two approaches.
The first approach is to circumvent the problem, with a side benefit of cool animation. Since I have no clue when or how many times or exactly how iOS enforces the auto-constraints, I simply delay my UIView modifications and smooth it out with animation. So I wrap view animation around the code in my selector:
[UIView animateWithDuration:.25 animations:^{
CGRect rect = self.usageView.bounds;
rect.size.width = self.someCalculatedwidth;
[self.usageView setFrame:rect];
[self.usageView setNeedsDisplay];
}];
Then I'd call my selector in my controller's viewDidAppear:animated:
[self performSelector:#selector(resetUsageView) withObject:self afterDelay:0.0];
Now most would say this is a cop-out or a kludge. And that's fair.
In the second approach I attack the root of the problem - auto layout/constraints. I add a Width constraint to my usageView in the storyboard, and connect its IBOutlet to my code.
#property (weak, nonatomic) IBOutlet NSLayoutConstraint *usageViewWidthConstraint;
Then I modify the constraint as per the calculated width in my controller's viewWillAppear:animated:
[self.usageViewWidthConstraint setConstant:self.someCalculatedWidth];
Voila! A one liner.
Now what if I want animation given I got a taste of it from the first approach? Well, constraint changes are outside the realm of animation so basically I'd need a combination of the first and second approaches. I change the UIView's frame for animation, and modify the constraint as well to "set the record straight":
[UIView animateWithDuration:.25 animations:^{
CGRect rect = self.usageView.bounds;
rect.size.width = self.someCalculatedwidth;
[self.usageView setFrame:rect];
[self.usageViewWidthConstraint setConstant:self.someCalculatedWidth]; // <<<<
[self.usageView setNeedsDisplay];
}];
I've been pushing myself to learn more MVCS styled programming and am attempting to organize my code better. My main question, is I have a UIViewController that brings up a view when an event occurs. When the view is created and when the view is destroyed, I'd like to run some animations on the view appearing and disappearing. I can do this both in the UIView class I have and in the UIViewController. Once these animations have been established, they do not need to be changed. Should I do this within the UIViewController or the UIView to stay MVC compliant?
The code is currently in my UIView as such:
- (IBAction)removeView
{
NSLog(#"Remove");
if (self.completionBlock != nil) {
[UIView animateWithDuration:1.0f delay:0 options:UIViewAnimationOptionAllowUserInteraction animations:^{
self.transform = CGAffineTransformMakeTranslation(self.frame.origin.x, self.frame.origin.y - self.superview.frame.size.height);
self.alpha = 0; // also fade to transparent
}completion:^(BOOL finished)
{
if (finished) {
[self removeFromSuperview];
}
}];
self.completionBlock(YES);
}
}
Based on your description, you can legitimately do them in either place because the animation does not depend on your application's model. If, however, the animation depended on data from your model, then the controller should perform the animation because the controller sees the model data (but the view does not).
The Views of the ViewController should be the ViewController's minons. You're going to have an easier time having the animation maths happen in the ViewController and have the ViewController update the View and this is the best practice according to MVC.
Also, I think it will be easier for you because you can make the logic based on an action as opposed to based on a class. I find that easier.
In fading a view controller in from black, I am doing the following within viewDidLoad:
Creating a UIView with a black background;
Giving the UIView an alpha value of 1.0f;
Adding the UIView as a subview of [self view];
Fading the black UIView out via animateWithDuration by changing its alpha value to 0.0f; and
Removing the black UIView from [[self view] subviews]
More often than not, this works as planned. Occasionally, however, I see a glimpse of the view controller I want initially hidden, just before the black UIView is drawn.
Is there a way to avoid this? Is there a better method to place this code in than viewDidLoad?
Many thanks
Yes, add the view in the loadView method and do the actual animation in viewDidLoad or viewDidAppear. Or do as the above commentor said and simply use the view alpha.
I would create the UIView that I want hidden in UIViewController's nib file, then link that to via an IBOutlet
#interface SomeViewController: UIViewController
{
IBOutlet UIView *blackView;
}
then in UIViewController's -(void) viewDidLoad; method, I would do the following
- (void)viewDidLoad
{
[super viewDidLoad];
// Fade the opacity of blackView over 1 second,
// then remove it from the view controller.
[UIView animateWithDuration:1
delay:0
options:UIViewAnimationOptionCurveEaseOut
animations:^{
blackView.layer.opacity = 0;
}
completion:^(BOOL finished) {
// This line prevents the flash
blackView.layer.opacity = 0;
[blackView removeFromSuperview];
}];
}