I've got an UIScrollView and in it different images (about 30). I'd like to make it possible, when user reaches the last image to show the first one after it and so on. And I want to implement the same feature with the first image (to go to the last one). I'd like to loop the images smoothly that user won't even notice that he is making another loop.
Here's an article on how to do it. It describe how and also include code - even if it's in Objective-C (but it should be easy to convert to C#).
Related
I would like to know when the screen is being drawn on iOS. In particular, I'd like to know if there are any visible changes being drawn on screen. This can be handy to know how long a page took to render, for example (assuming that the user is not interacting with the page). I would like to be able to capture this information in a regular production build, not in a developer build. And I'd like this to be a general solution applicable to most any page in my app, not just a specific page.
For example, I have a page that 1) asynchronously queries an API for data, 2) displays that data in a UITableView where some of the entries may be offscreen, and then 3) asynchronously downloads the images for each of the visible items on the screen. I want to get callbacks when the UITableView is rendered and when all of the images are rendered. The total time to render the page can be determined by looking at the timestamp of the last call to the callback (again, assuming no user interaction).
On Android, this is fairly simple. You can use ViewTreeObserver.addPreDrawListener to get a callback whenever the screen is being drawn. If there's no visible change to the screen, the callback is not called.
On iOS, it looks like CADisplayLink might potentially serve a similar purpose. However, when I hook up my CADisplayLink, it appears to be called over-and-over forever, whether or not there are visible changes on the screen.
Is there a way to know when there are visible changes to the screen being drawn in iOS?
In iOS 9 Apple made it impossible to get access to things drawn onto the screen outside of your app. Prior, it was possible to use an API called IOSurface to do it, but Apple closed it down in iOS 9. (To prevent apps from snooping on each other.)
So if you're talking about ANYTHING being drawn to the screen the answer is no. If you're looking for changes within your app there's probably a way to do it.
Originally I had a different post, just wanted to redo it to clean it up.
This is more or less the layout I wanted to go with. Imagine the first imageview had dog pictures, the second one had cat pictures and the third one had rabbit pictures. three folders contain a group of three separate sets of pictures.
What is the best way to set it up so I can randomly swipe, lets say the first image view where it would only show pictures of dogs.
What I am asking is, is there a certain way to create the file structures or link the pictures to each image view?
I have the basics of the random (something with a 4 in it don't remember the method exactly) and the basics of swipe, just was looking for help with linking the photos and file structure.
Please let me know if this still doesn't make sense.
Thank you
EDIT
after messing with this this is where I am at:
with a very simple array basically
catsArray: [String] = ["catpic1","catpic2"......]
then I have it set up as
let randomIndex = Int(arc4random_uniform(UInt32(catArray.count)))
if (sender.direction == .Right)
{
self.catImageView.image = UIImage(named: catArray[randomIndex])
}
just me hacking things off the internet. now I am running into an issue. after a few swipes I get a null images or its just blank. Why is that?
now that I have some of this set up I am debating if I should just use parse for a server or if there is a better way.
thanks
Either approach will work. It's probably a good exercise to write both versions. You'd learn from it.
Your question is far too vague. Are you worried about memory? If so, you should not load the images into an array. Instead load the image names, and load each image as it is swiped on-screen. You might want to load the current image and the next image so it's already in memory and can be displayed without lag.
Are you talking about using a UIPageViewController? That's a good class for managing a set of pages that you can scroll through. There is a sample app from Apple called PhotoScroller that illustrates that technique, along with tiling the images so you can display large images and handle zooming and panning. (The app is written in Objective-C however.)
EDIT:
Your updates make your question a little clearer.
There are lots of ways to handle this. Here's 1.
Create 3 separate folders, one for cats, one for dogs, and one for rabbits. (in your app's documents directory, or in the bundle, if the images will be shipped with the app.)
Use NSFileManager to create 3 separate arrays of filenames. Take a look at the methods contentsOfDirectoryAtURL:includingPropertiesForKeys:options:error: and contentsOfDirectoryAtPath:error:. You should be able to make either of those work.
Then you'll need to scramble your arrays of filenames to create a randomized order. You can use one of the block-based sort methods where your block uses a random number to determine the sort order of each pair of objects.
Finally you'll need to implement the swipe to switch.
It sounds like you are beginner so this is a lot to work through. You should break the problem into pieces and tackle them one at a time.
I am using Xcode 6 and coding in Swift. I am relatively new to Swift but have programming experience in C.
I am creating a column of random numbers which I display by programmatically creating image views with the appropriate number image.
My logic is as follows:
User presses a "spin" button
A function is called which creates a column of random numbers (ex: say 5 numbers) and displays the appropriate number image for each.
Instead of just generating my 5 numbers, displaying them and leaving the function, I put this in a loop that will process 100 times.
The purpose of the loop is to create a "spinning" effect.
This is where my problem arises. I do not get a spinning effect, instead I simply see the last 5 generated numbers that were displayed.
As best as I can tell with my limited understanding of when things occur, it seems as though the images don't actually update until the function (which was called by the user tapping a button) completes and returns.
Is this true?
If so how can I create my "spinning" effect?
How can I get the numbers to display at the time I generate and assign my number image?
This is the first time I've used this forum (as far as asking a question) and apologize in advance for anything I've done wrong when laying out my question.
Thank you - Ed
As the application loads, I want to make an image load at the same time, for example, a line would elongate form either side as the application loads, and when it has finished, the line would have reached its maximum length. I have seen this in a few websites, like rime arodaky for example, but I want to this for an iOS application. I have searched on Google but couldn't find anything!
Does anyone know how to do this?
The launch process if we REALY simplify it to accommodate your question, can be split into two parts.
The first part you do not have any control over, and during which a launch image is shown.and it ends with a delegate call-back on the application delegate called
applicationDidFinishLaunchingWithOptions
The second part is you might have some application specific behaviour which requires no activity from the user but you app still isn't interactive.
You need to implement such a progress bar yourself. There is no built in support for this in any of the app templates in Xcode.
You can only do what you want during this second phase. But you have absolutely no control over the first phase, except for that static non-animated launch image.
I think you can just add a photo as a launch image, launch image is just an image.Then you can add the animation when your first view controller appears.You can fake it this way.
I'm new to ios, and I've already got my design ready, now I don't know is there a best practice for me to do the following thing:
I have 1000 cards, each of it is like this:
And when I slide right, it will get the next one, I slide left it will back to the previous one
I can implement this now, but I can only implement this one by one for 1000 times.
In addition, when I click the middle of the card, it will flip horizontally, then show the translation. it's the second kind of card with different language and color.
So is there any hint for me? any loop can do it?
update
About data-drive, so I thought about database, and I search the google that there's four way of persistence in ios,
I decide to choose sqlite, is it a wise choice?
Reason:
I'm familiar with mysql, and use sqlite in rails before
sqlite is not too big.
I need to save original sentence, translate sentence, saved or not flag, additional story.