I have an app with a draggable UIView placed at the bottom. The draggable view isnt totally offscreen and it has a "pull tab" that the user can drag upwards or downwards. Dragging up and down currently works, but I would like to give it the same behavior as the Apple notifications slide out drawer.
For example, if I drag the view out 50% upwards and remove my finger from the screen, then I'd like the draggable view to continue to move upwards on its own. Likewise, if the user only dragged the view out, say 30% upwards, then the view should drop back down to its default position.
Ideally, while I can do the dragging up/down, the motion isnt very "organic"....
Right now, I'm accomplishing the dragging upwards and downwards via UIPanGestureRecognizer, just in case that's relevant to the question.
Is it perhaps something along the lines of some clever math with the Y position of the draggable view, then doing the rest of the moving with some CAAnimations?
It might be a bit hard to visualize, so I've added some screens below.
Default screen with the a view at the bottom
The view dragged up via the tab on the right
Thank you!
When your UIPanGestureRecognizer's state becomes UIGestureRecognizerStateEnded, use the velocityInView: message to find the velocity of the gesture.
If the velocity is close to zero, open or close the view based on the position of the view and the previous state of the view. For example, if the view was closed and it has been pulled out more than 10%, open it. If it was open and has been pulled in more than 10%, close it. Otherwise, move it back to its pre-gesture position.
If the velocity is not close to zero, use the sign of the Y component to determine the new state of the view. If the sign is positive, close the view. If the sign is negative, open the view.
You will have to experiment to figure out exactly what definition of “close to zero” feels best.
In any case, you will want to animate the view to its final position after the gesture ends, using a short duration (probably between .1 and .25 seconds). You may want to choose the duration based on the velocity and the distance the view needs to travel. The system notifications panel does this. (Try dragging it partway down slowly vs. rapidly. It animates to its final position at different speeds depending on how fast you were dragging it when you let go.)
You will want to experiment to find the best animation curve (UIViewAnimationOptionCurveEaseOut, etc.), and you may want to use a different curve depending on whether you're opening or closing the view and the velocity of the gesture.
Related
I am trying to create a menu for my app with a few icons in a circle. User should be able to spin this menu, making the icons change their positions around this circle path, but not rotating themselves. I read this earlier http://www.raywenderlich.com/9864/how-to-create-a-rotating-wheel-control-with-uikit so I can see how to follow the finger movement, but I need this menu to have inertial spin after the touch ends. I have 2 questions about how to do this.
First one, what's the best way to make animation with icons moving around in a circle? It should be slowing down until it stops and, if user moves his finger fast enough, should be able to do more than one full circle.
Second, how do I measure speed of finger movement at the end of it? I tried to use locationInView and previousLocationInView and just spin it by difference of angles between them multiplied by some constant. Problem is, when I keep my finger in one place for a while and take it up, I still get inertial movement of the circle and in this case I don't want it to move at all.
You want to use a scroll view. Specifically you want a hidden scroll view where you attach the pan gesture recogniser from the scroll view to your custom menu view. Then you implement the delegate methods of the scroll view to redraw your menu. This WWDC video has a good overview of the process. The benefit of this approach is that you get true iOS style acceleration and deceleration for free. You don't need to worry about finger position or speed, only the content offset of the scroll view.
Unless you want to spin your finger round in a circle with the menu items. That's a different ball game...
In theory, the same approach as above can be used for spinning your finger in a circle. You would need to ensure that directionalLockEnabled was set to NO on the scroll view. The problem is that the calculations to determine the rotation of your menu view are a lot more complex. Probably you would want to be modal and check if the scroll view is dragging in the callbacks. If it is dragging you would use the touches on the pan gesture to find the exact finger location to set the rotation. You'd also want to maintain data on the instantaneous direction of finger movement so that when the touch is released... If it isn't dragging then you use the scroll view content offset to apply the deceleration effect on the rotation (using the scroll direction just before the touch was released to know how to use the content offset changes).
I would like to create view that could be pulled from one corner to take full screen (like the iphone status bar that can be pulled from top).
Could you just give me an idea how to accomplish that.
Thanks
Put a small view into the corner of the screen that acts as your handle.
Add a UIPanGestureRecognizer to that view.
When the gesture recognizer's action method gets called, move the handle and the view you want to present according to the movement of the user's finger.
When the gesture ends (because the user has lifted their finger off the screen), decide whether the movement was large enough to bring in the new view or not (e.g. if the user dragged the view over >30% of the screen, you move it in, otherwise you move it back out).
Animate the view into its final position.
I'm looking for a way to slide a partially concealed tool panel from off screen like the JetBlue iPhone app does. I know how to do this with regular swipe gesture recognizers, but that app has a certain threshold, after which the panel "snaps" to the on-screen position, otherwise it hides back offscreen.
How can I implement this kind of swipe-to show, but with a threshold kind of gesture recognizer? Are there any open source projects that do this kind of UI manipulation?
I have a similar interface element in an app I've written. My interface element is a UIViewController for the entire tool panel. I put a UIButton over the gripper illustration, change the button's type to custom so it visually disappears. I connect Touch Drag Inside and Touch Drag Outside to an IBAction that adjusts the position of the panel according to where the drag moves. I connect Touch Up Inside and Touch Up Outside to an IBAction that finalizes the positioning of the view. If the touch up event happens too close to the bottom, I just close the panel. If it happens anywhere higher than that threshold I open the panel. I use UIView's animation methods to smooth out these transitions. The over extension element seen in the JetBlue app can be accomplished in the drag event handler. As the panel gets closer and closer to the limit, open the view a smaller and smaller amount with each move of the touch higher. Then in the finalization, just animate the panel back down into it's preferred ending position.
The JetBlue app differs from my app in that I have a small gripper area, but JetBlue's app allows you to swipe the whole panel to adjust position. To match that functionality, I would adjust my implementation to totally cover the panel with buttons. Each would respond to my drag events with the addition that dragging would set a flag. Then my touch up event handler would check if the flag was set. If so, finalize the dragging of the panel. Otherwise, perform the appropriate action associated with each button.
If you can already implement the basics with gestures, then you're almost there!
To be honest, while I've done exactly this in my application, I use the old fashioned touchesBegan, touchesMoved, etc.
In terms of gestures, you'll have to use UIPanGestureRecognizer so you can have full control of the drag. UISwipeGestureRecognizer only recognizes swipes.
Anyway, after a certain point, you simply translate the panel only a fraction of the distance the person dragged.
CGRect newPanelFrame = panel.frame;
if (newPanelFrame.origin.y + dragOffset > 275) {
newPanelFrame.origin.y += dragOffset / 2.0;
}
panel.frame = newPanelFrame;
In touchesEnded:withEvent: or if (gestureRecognizer.state == UIGestureRecognizerStateEnded)
CGRect newPanelFrame = panel.frame;
if (newPanelFrame.origin.y > 275) {
newPanelFrame.origin.y = 275;
}
panel.frame = newPanelFrame;
The reason why I've never bothered with the UIPanGestureRecognizer is because I could never figure out how to get the non-cumulative translation (translationForView: is cumulative), which is necessary if you want to essentially slow down the drag after the threshold.
I was just doing some research into achieving a similar effect, stumbled across this post, and as a result decided to give JetBlue a try.
After playing with the sliding panel for a bit, I'm actually thinking the JetBlue guys actually went about this in a slightly more different manner.
The motions of the slider in the JetBlue app seem to handle much nicer than what you could do with a collection of UIGestureRecognizers; it's capable of animating at different velocities depending how quickly the user swipes it, and the rubber-banding compensates for this properly too.
So on that note, I actually think that they're not using UIGestureRecognizers, but that panel is actually just a standard UIScrollView aligned to the bottom of the app window, and with a bit of extra logic (probably applied via the delegate) that just makes sure it isn't possible for the scroll view to stop animating between the 'open' and 'shut' state.
Ok, I have a complicated scenario here. I have a scrollview which scrolls horizontally and contains tiles, 1 centered on the screen at a time with the user still able to see if there are more to the left or right by way of having the edges of the 2 views visible on either side. I am able to add the views programmatically to the scrollview and have paging work properly, so the user can swipe back and forth between them. Another requirement is to have an initial animation where the first view slides in, then is bounced off to the left by the second view. I accomplished this by using a series of UIView animations, and it works well.
Here is my problem: After the animation completes, you cannot scroll left to get to the first UIView that was created. I suspect that this is because it was animated out to the left of the content area of the scrollview. I have tried to increase the contentSize of the scrollview, but I still get the same behavior.Once the initial scrollview has been moved off to the left, I cannot swipe to page to it.
Is there a common pattern I could use to accomplish this in a better way?
It sounds to me like you're animating the child view's frame to the left so that the x coordinate of that first view's frame is negative, instead of animating the scroll view's contentOffset to the right. If that's the case, is there a reason you aren't just setting the scroll view's contentOffset inside an animation block? If there is a reason, what if after the animation completes you "fix up" the content offset and the frames of the child views so that none of the views are in a negative position.
But, I guess I have more questions than answers right now, so it might help to post the code showing how you do your animations to make it easier to answer your question.
I have a 320x416 portrait-shaped UIWebView filling a UIViewController's view. I also have a 90 degree rotate button that will transform the UIWebView through 90 degrees each time the button is touched. The code is basically:
webView.transform = CGAffineTransformMakeRotation(touches%4 * M_PI/2.0);
After rotation through 90 degrees, the now-landscape transformed UIWebView extends beyond both the left and right edges of the screen. In the process of applying the transformation, iPhone OS has changed the UIWebView's frame from {{0,0}, {320,416}} to {{-48,48}, {416,320}}. Don't have a problem with that.
I then tweak the UIWebView's frame origin to (0,0) so that it starts top-left, but extends a little further beyond the right edge of the screen. Now, I can touch the UIWebView and pull it left to view the hidden information on the right but I cannot get the right-hand end to to stay on the screen -- the moment I untouch it, the right side bounces back off the screen.
What is it that causes the view to bounce back off-screen? In other words, what is it that I need to tweak to allow either the left edge or the right edge to stick on the screen and remain visible (only one at a time, obviously)?
Thanks.
As far as I understand what you've done in your project, what you are seeing is the normal behaviour of any scrolling window in iPhoneOS. That is, your UIWebView is wide enough to contain all the HTML content displayed within so while it will move when you drag it, it springs back to its original position when you let go. The fact that the UIWebView is wider than the screen due to the fact that you've rotated it, but not resized it, means that you can't see it all the HTML content, but as far as the UIWebView is concerned it's all visible so it doesn't let you properly scroll it, it just bounces.