I am writing an app which is going to be displaying images found on my server in a UIImageView.
I need something that will asynchronously download the image and cache it while putting it in the UIImageView.
The download also needs to be able to be cancelled when I press a button.
Can anyone point me in the direction of something that can do this?
In the old times the framework for that was ASIHTTPRequest but is an abandoned project now. This https://github.com/AFNetworking/AFNetworking seems to be popular now.
Use the performSelectorInBackground:withObject: - method from NSObject ;)
Advise: The updating of the view must run on the main thread!
http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/nsobject_Class/Reference/Reference.html
Related
My problem is simple: I'm waiting to take a screenshot of an MKMapView, and I want to do it only once the map is loaded. Unfortunately, this delegate method is almost always called before the map is actually loaded. I just get a grid, or a few loaded tiles if I'm lucky. Is there a good way to do what I need to do? Or am I missing something in the MKMapViewDelegate protocol?
Thanks!
Perhaps you could try adding a timer and then take the screenshot in the completion block of the timer. Or perhaps, use the mapView:didUpdateUserLocation: delegate method as the callback for the screenshot instead of mapView:DidFinishLoadingMap:
It seems this is one of the many bugs in MapKit in iOS 6. Hopefully it will be fixed with iOS 7.
Is there a quick and easy way to have the app go back to the same screen after I put it in background mode?
I know there are frameworks just for this stuff, but has anyone done it without much sweat?
Thanks
In your app delegate, add a line to the applicationDidenterBackground: method that stores the current page via NSUserDefaults.
Then in the applicationWillEnterForeground: method, load up that saved value and restore the page.
Multitasking should enable this, while a device has enough memory to keep your app open. Otherwise how about using NSUserDefaults to store a string reference to your view?
As of iOS 5.1, there is no quick and easy way.
At the moment, I have a goal of writing an application that contains a UIImageView. Upon loading or pressing a button, an image from a web server will load into the view.
What is the simplest way to do this? I'm assuming using the API described here? https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/URLLoadingSystem/Tasks/UsingNSURLConnection.html
In the mean time, I will continue to try to get this working on my own. Any advice would be appreciated, especially if you have written code like this before.
Yes, this can be done by making a request through an NSURLConnection.
You might be interested in checking out SDWebImage. This library includes a category that adds a method to UIImageView that makes asynchronously loading an image from a remote URL as simple as this:
[self.imageView setImageWithURL:[NSURL URLWithString:#"http://www.domain.com/path/to/image.jpg"] placeholderImage:[UIImage imageNamed:#"placeholder.png"]];
I'm working with a webview within a window of a Cocoa application. I would like to retrieve some values using stringByEvaluatingJavaScriptFromString on the webview and save them before the application shuts down. I tried using the applicationWillTerminate but by the time I reach this method, it is too late. I was wondering if there's something built into webview that I've missed or if anyone has an elegant solution to share.
If you want to save this information, why are you waiting until the app is about to terminate?
My App is a view-based application. At the beginning I show my logo and after a delay of a few seconds it changes into another view. from then on the user can switch to a lot of different views.
Sooooo.. My Problem: The thing is, when I restart my App. [..well closing and reopen by touching the icon..] the app itself doesnt restart in the sence of jumping to the very first view. to the contrary: at restart the user just returns to the last view that was open.
So I dont know why this is.
Is it normal to somehow manually tell the app to return to the very first view after restart? And if so, how do I have to do that?
PS.
I have so no idea what to do.. Maybe my problem has to do with the timer i used in the first view to change after a delay of time?
Please, is there anyone, who can help me?
Your problem is that, as of iPhone 4, returning to the home screen does not terminate your app. It's just made inactive, so opening it again reactivates it. In most cases, this is a good thing. If it doesn't work for your app, you can add the UIApplicationExitsOnSuspend key to your Info.plist with a value of YES.
(As I said, you should only do this if it really helps usability. If it's just about getting your splash screen shown again, most users and possibly Apple will frown upon it.)
iOS 4.0 and greater have a fast-start thing that allows apps to restart back from where they were upon restarting. There are several ways to deal with this:
1.) your App Delegate receives info about being but into the background and resumed. - (void)applicationDidBecomeActive:(UIApplication *)application and - (void)applicationDidEnterBackground:(UIApplication *)application are the relevant functions here. Check the docs.
2.) You can also disable the background, inactive state completely by including UIApplicationExitsOnSuspend in you Info.plist as Chuck already pointed out.
Overall, you should check the application state docs on Apple's Side.