I'm making a dictionary app, which allows user find a word definition by touch the word in screen, and there will be a magnifier on screen and follow user's finger. I have implement it by take a screenshot of view and assign the image to maginifer image view, which is a UIImageView, however, in order to take a screenshot, the method [self.layer renderInContext:c]; cost too much time, is there any other way to do it ?maybe openGL will help?
after profiling my app with instruments->core animation, it is only 9 fps showing magnifier, but it will 30 fps if showing the system default magnifier in a UITextView, I don't know why the system is so fast
You can use exact same view in magnifier view, and change position to visible words.
There are new methods in iOS 7 that are highly optimized :
– snapshotViewAfterScreenUpdates:
– resizableSnapshotViewFromRect:afterScreenUpdates:withCapInsets:
– drawViewHierarchyInRect:afterScreenUpdates:
However they are not available in previous versions.
Related
I'm making a react-native based app, and I can partially use Swift code by react-native's NativeModule feature.
My app will be used as Split view / Slide over mode in iPad, and I want to know if my app is in the left-side, right-side, or Slide-over.
I could get width and height, also origin (CGPoint) by this code.
let window = UIApplication.shared.windows.first
// Then getting X, Y like this...
window.frame.origin.x
Now my app has only one webview, made by react-native-webview.
So I guess, since the webview is the whole content of the app, and it fills app 100%, so it always returns app.
I want to know, not in webView's perspective, but in app's perpective, the POSITION relative to the screen.
For example, if my iPad width is 1400, and if my app is on the half right side, x should be 700.
And if it is on left side, it should be 0.
I really struggled this, but couldn't find any solution.
FYI, I drawed a diagram for this question.
As I wrote on the above, I tried UIApplication.shared.windows.first.frame.
But it only show the CGPoint of webview, not app relative to the screen.
There is no API for getting 'X' or 'LEFT' in react-native-dimension too.
onLayout also not helpful.
In iOS 16, Lock screen widgets allow you to add an Image to the WidgetView, like in accessoryCircular.
How do you animate this Image? Loading the Image from an animated UIImage with frames just displays the first frame.
Am I missing a startAnimating call, like you have to do with WKInterfaceObjects? Is there some additional step or value to set to get an Image inside a SwiftUI WidgetView to begin animating, or cycling through frames?
Examples of apps that have achieved this are https://www.livelywidget.com or Pixel Pal, so I know it's possible, but when I search for APIs to accomplish this, all that comes up are apps.
iOS 11 has an accessibility feature that shows a large version of a tabbar icon in a pop-up HUD when long pressed. In a WWDC presentation, it was mentioned this just involves turning on:
Settings -> General -> Accessibility -> Larger Text
..and adding:
tabBarItem.largeContentSizeImage = UIImage(named: "myHud")
Alternatively, you can add a vector image as the main tool-bar image, with 'Preserve Vector Data' checked in the asset catalog.
I've tried all combinations of this, and a long press does not show the HUD. I also tested with the Files app on my iPad running iOS 11b4 with no luck. This is the app that was demoed at WWDC.
Is there some other accessibility setting I'm missing to enable this feature? Or is it not available in beta 4?
It isn't enough to turn on Larger Text. You also have to use Larger Text — i.e. slide the slider way to right.
Then it works — well, the HUD appears. But the icon is not being enlarged within the HUD, so I don't quite see the point:
(As you can see, I'm doing this in a test project where I'm experimenting with the vector PDF image feature.)
This feature implementation and an example with tab bar are perfectly explained with illustrations on this accessibility site but here are the outlines :
Under Xcode, import the image to be enlarged with a pdf extension and a x1 resolution in the xcassets catalog.
In the new Image Set, tick Preserve Vector Data and specify Single Scale as Scales attribute.
If a storyboard is used for this image, tick Adjusts Image Size in the Image View section, otherwise put the adjustsImageSizeForAccessibilityContentSizeCategory image property to true in code.
For your tab bar or tool bar used in the application, first repeat the previous 3 steps for each image included in the items to be enlarged in the middle of the screen and then link the accessibility image to its appropriate item.
This feature is available only for the accessibility text sizes.
WARNING : don't forget to check your layout with these new images larger sizes.
For your record, an explanation of the Large Content Viewer is provided in this detailed WWDC video summary if need be ⟹ the UILargeContentViewerItem protocol is an iOS 13 new feature that shows the same HUD that's shown for standard bar items.
You need to go :
Settings > General > Accessibility > Larger Text(set on) > Move slider more then half to the right
Don't forget to set
tabBarItem.largeContentSizeImage = someKindOfImage
And Long press will does the trick.
I have a UICollectionView whose cells each have an AVPlayerLayer, all playing a video at the same time. About 9 cells fit on the screen at a time and it's pretty laggy so I need ways to boost the performance to achieve smooth scroll. There's a few things I've tried already:
1) Each cell has only one instance of AVPlayer. It doesn't get created, instead, player.replaceCurrentItemWithPlayer is called when the video url changes.
2) Because I'm using ReactiveCocoa, it's trivial to skip repeat urls to avoid playing the same video twice.
What else can I do to speed up the scroll and performance?
First I want to say it's a bit crazy to see several players in action at the same time: it's a heavy task of rendering anyway.
As far as I know, simply scaling/re-framing the video to smaller size doesn't make it less content to render: if you have a 100x100 picture to render and you render it in a frame of 10x10, it still consumes the same amount of memory as the original picture would consume; same thing goes for videos. So, try to make your video assets having similar resolution as the frame where you would present them.
Store each cell in an NSCache or NSMapTable using the NSIndexPath as the key for each; then, whenever you need a cell, call one directly from the cache or map table.
Obviously, you'll have to create all the cells at once, but you'll get the same scrolling performance as you do with nothing in the cells at all.
Need sample code?
Here's my latest iteration of a perfectly smooth-scrolling collection view with real-time video previews (up to 16 at a time):
https://youtu.be/7QlaO7WxjGg
It even uses a cover flow custom layout and "reflection" view that mirrors the video preview perfectly. The source code is here:
http://www.mediafire.com/download/ivecygnlhqxwynr/VideoWallCollectionView.zip
Unfortunately, UIKit will hit bottlenecks and drop frames when put under pressure for this use case. If you can muster refactoring code to use Facebook's AsyncDisplayKit / then this would be your best bet.
For objective-c / this project here is a good reference.
https://github.com/TextureGroup/Texture/tree/master/examples/ASDKTube
- (ASCellNode *)tableNode:(ASTableNode *)tableNode nodeForRowAtIndexPath:(NSIndexPath *)indexPath
{
VideoModel *videoObject = [_videoFeedData objectAtIndex:indexPath.row];
VideoContentCell *cellNode = [[VideoContentCell alloc] initWithVideoObject:videoObject];
return cellNode;
}
there is swift code available if you dig deep enough in github.
Every time when we add UIImageView or simple UIView with some custom CALayer objects added to "layer" property to view hierarchy, there are some different scenarios:
1) all images (in uiimageviews and calayer) are drawn with random delay
2) some images are drawn, but some not, when we perform a simple touch event anywhere - they appear
3) some images are not drawn and they won't appear after simple touch events, the only way make them to appear is to minimize the app and to expand it again.
The last case appears much less than two others. That problem occurs only on iOS7, iOS 4.3-6.1 is totally OK. We have viewed a lot of possible solutions but they were pretty primitive and none of those helped.
Any help would be appreciated! Thanks in advance!
we solved the problem. For everyone, who has the same problem, - all you need is to create CALayer and UIImageView objects on main thread, while UIImage objects still could be created in background thread. All these fixes are needed only in iOS 7