I can not animate many images with animationImages and startAnimating as it uses too much memory and crashes. What is the best way to animate 100 images in a portion of my iPhone screen (not full screen)? Is there an example?
I think you have two solutions :
1°) Subclass UIView and in the drawRect you draw each time another image. You add a NSTimer to create the animation ^^
2°) Do the same as 1°) but with OpenGL ^^
Good Luck ! :-)
Related
I'm trying to create a crossword app. The game runs in a UIScrollView, because the player should be able to zoom, scroll etc. The largest crossword are 21x21 which means there need to be 441 touchable tiles. What i've tried so far were to create an UIView and added it as a subView to the UIScrollView. Then I call a method that creates 441 custom UIButtons and set the backgroundImage.
Some of the UIButtons need to have a custom label overlay, so i added a UILabel and set it on top of the UIButton.
When I run the app in simulator all works as it should, but when i test it on an iPhone 4 the UIScrollView lags a lot.
I don't know if this the way to do it? Can you maybe try to guide me in the right direction of how to do this so the UIScrollView won't lag on a device.
Thanks in advance.
Big UIScrollViews are difficult to make smooth without some sort of caching mechanism, such as the one provided by UITableView.
One thing you can do, however, to make life easier for your rendering, is to make sure to use opaque backgrounds whenever possible. In stead of making a view transparent you should make it the same color as its underlying view. This is something that does help.
Also, I have experienced better performance using imageWithContentsOfFile: in stead of imageNamed: for initializing images to be used in a UIScrollView.
In order to not keep all those buttons in memory, you should work with reusable table view cells, this will really improve the scroll performance. Here's one component that could make your life easier: DTGridView, there are also others (you can check Cocoa Controls)
I've got a pretty big UIScrollView (contentSize 8000 x 960) with a lot of small labels.
The labels are only added if you scroll to the area where the label belongs to. So, at first, the scrooling is smooth, but as more and more labels are loaded, the performance suffers more and more.
What's the best solution to keep the scrolling smooth? Is CATiledLayer the way to go? Or should the labels off the view should be hidden or something like that?
Thanks a lot for your help!
Stefan
EDIT:
I got a huge performance boost when drawing some objects instead of using views; but now, I've got another problem; if I draw directly onto the UIScrollView, everything performs great. But if I lay a UIView on the UIScrollView and draw on that, performance goes down again (both times calling setNeedsDisplayInRect: in scrollViewDidScroll:).
So hierarchy:
UIWindow
UIView
UIScrollView <== drawing here
works fine.
But hierarchy:
UIWindow
UIView
UIScrollView (size 8000x960)
UIView (size 8000 x 960) <== drawing here
performs bad.
Any ideas why? I need the UIView above because the drawing should be ABOVE some UIViews; so I place the UIViews in the scrollView and draw in the view above...
The label reuse is one of possible solutions. Sometimes it doesn't help a lot. When a new UIView appears the drawRect method will be called and that may cause problems with animation.
Sometimes the best solution is to draw your labels (I mean text) directly using Core Graphics without creating UILabel object or something else. The CALayer will increase performance, but there is a possibility that it will not help you a lot.
But first of all you should remember that views with alpha = 0 or hidden = YES will not be drawn at all, so there is no penalty for using them. Maybe you should try to hide unused ones before using Core Graphics.
The best way would be to have just a few UILabels and reuse them. But you'll have to implement - (void)scrollViewDidScroll:(UIScrollView *)scrollView and do some reusable logic there. Depending on case it might be easier to use a UITableView and transform it 90 degrees, so it looks like a scrollview. That way you can the build-in reusable logic of the TableView.
For others seeing this post, I was able to drastically improve performance and keep UIViews in a scroller without using a table by enabling each view's "shouldRasterize" property. This property renders the view as an image while the view is in motion, causing it to not need to be reprocess for each pixel it moves. So, if I have a UIButton called button, it gets enabled like this:
button.layer.shouldRasterize = YES;
Did u try something similar to UITableViewCell
dequeueReusableCellWithIdentifier
Using a reuseIdentifer to reuse the once allocated labels..
I'm trying to display a series of images in a animation where the duration between the images changes frame to frame. I can successfully animate images where the duration is the same. I've looked into subclassing UIImageView but it doesn't seem to allow you access anything that could be helpful.
I've also looked into subclassing UIView directly but it seems like I'd have to write a lot of the stuff that UIImageView already does for me.
Is there a way to do this with UIImageView? Or if I am going to have to build my own UIView animation can someone point me the right direction to get started? Thanks.
You could have many UIImageViews next to one another, each representing one image, and animate them inside a UIView or UIScrollView, depending on what exactly you need to do. Animations with the help of UIView are very straightforward to implement.
Is there anything faster than UIView Animations? Mine are not keeping up,
I want to play a series of images, very fast. (i.e 10 in 80 milliseconds)
Any ideas?
As usual, greatly appreciated.
Sam
If you are looking for a replacement for UIImageView's animationImages property, the second example on this page presents an alternative (as pointed out in this question).
Do you mean the UIImageView animation images? Do you want transitions between your images? If not, there is no reason to use UIView Animations.
Now to play frame-based animations, I would suggest using the UIImageView object and add your images in its animationImages array. Not sure it will keep up with the framerates you require of course, especially if the images are large.
I need to play frame based animations. I tried the UIImageView with animationImages but it doesn't give me any control over my animation. I can't pause it, I can't mask it, I can't know the current frame etc.
So I subclassed UIView and created something I called AnimationView which takes the array of images and does the animation using an NSTimer. In the drawRect: I can then do all the masking and everything else I want.
However this method is way too slow. I can't run an animation at 30fps, maybe not even at 10fps and I am testing on a 3GS. (I am only doing masking and blending on every frame :) - and using the same images plays fine at 30fps on a UIImageView).
So, what is the most efficient way to achieve this? Is the NSTimer a bad choice? Is there a better way around it?
Thanks :)
In this answer to this question Mo DeJong provides a link to a source code implementation of a class that manually animates PNG image frames. He claims to get 15 FPS for 480x320 images animating on a non-3GS iPhone.
The NSTimer is fine. The problem is that you're touching a lot of pixels using the CPU in every frame using Quartz (the drawRect:). What you want to do is either use OpenGL if you have to compose images using a mask or cache your images in CALayers or CGImages.