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Handling applicationDidBecomeActive - "How can a view controller respond to the app becoming Active?"

I have the UIApplicationDelegate protocol in my main AppDelegate.m class, with the applicationDidBecomeActive method defined.

I want to call a method when the application returns from the background, but the method is in another view controller. How can I check which view controller is currently showing in the applicationDidBecomeActive method and then make a call to a method within that controller?

Couldn't register with the bootstrap Server

I just changed some code in my program and got this error:

Couldn't register com.yourcompany.XXX with the bootstrap server. Error: unknown error code.

This generally means that another instance of this process was already running or is hung in the debugger.Program received signal: “SIGABRT”.

I tried restoring my program to a version that worked, rebooted, restarted, empty caches and rebuild on versions that even worked before.

Any help would be appreciated.

How to find unused images in an XCode project?

Has anyone a one-line to find unused images in an XCode project? (Assuming all the files are referenced by name in code or the project files - no code generated file names.)

These files tend to build up over the life of a project and it can be hard to tell if it's safe to delete any given png.

How can we programmatically detect which iOS version is device running on? [duplicate]

I want to check if the user is running the app on iOS less than 5.0 and display a label in the app.

How do I detect which iOS is running on user's device programmatically?

Thanks!

Detect Retina Display

Does iOS SDK provides an easy way to check if the currentDevice has an high-resolution display (retina) ?

The best way I've found to do it now is :

    if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)] == YES && [[UIScreen mainScreen] scale] == 2.00) {
         // RETINA DISPLAY
    }

iPhone: How to switch tabs with an animation?

I'm switching tabs programmatically in a tab bar driven application using UITabBarController.selectedIndex. The problem I'm trying to solve is how to animate the transition between the views. ie. from the view of the current tab to the view of the selected tab.

The first thought was to make use of the UITabBarControllerDelegate, but it appears that this is not called when programmatically switching tabs. I'm now considering the UITabBarDelegate.didSelectItem: as a possible hook to set a transition animation.

Has anyone managed to animate the transitions? If yes, how ?

Trying to understand CMTime and CMTimeMake

1) CMTimeMake(1,10) means duration of 1 second and timescale of 10, or 10 frames per second. This means 1s duration of video with 10 frames?

2)

CMTime lastTime=CMTimeMake(1,10);
CMTime frameTime=CMTimeMake(1, 10);
CMTime currentTime=CMTimeAdd(lastTime, frameTime)

= (2, 10) ?

2 seconds of video and with 10 frames per second of the currentTime?

how to change Xcode Project name

i have developed my app in xcode for iPhone , in start i have just named it without secnec now i want to change my app name i have replace my old app name with new one as i have found the name in my app , but its still giving me one error...

Desktop/New name/old name_Prefix.pch: No such file or directory

when i have change oldname_prefix.pch with newname_prefix.pch .. any idea ..

iOS - Calling App Delegate method from ViewController

What I am trying to do is click a button (that was created in code) and have it call up a different view controller then have it run a function in the new view controller.

I know it could be done relatively easily in IB but that isn't an option.

An example of what I want to do would be if you had two view controllers one with a splash screen of house. The other view controller had a walk through of the house on it that you could go through all the rooms in a set order. The splash screen would have buttons for each room that would allow you to jump to any point on the walk through.

Offline iOS web app: loads my manifest, but doesn't work offline

I'm writing a web app to be used offline on iOS. I've created a manifest, am serving it up as text/cache-manifest, and it usually works fine, when running inside Safari.

If I add it as an app to my home screen, then turn on Airplane mode, it can't open the app at all -- I get an error and it offers to close the app. (I thought this was the entire purpose of an offline app!)

• When I load the app a first time when online, I can see in my logs that it's requesting every page listed in the manifest.

• If I turn off Airplane mode, and load the app, I can see the first file it's requesting is my main.html file (which is both listed in the manifest, and has the manifest=... attribute). It then requests the manifest, and all my other files, getting 200's for all (and 304's for anything requested a second time during this load).

• When I load the page in Chrome, and click around, the logs show the only thing it's trying to reach on the server is "/favicon.ico" (which is a 404, and which I don't think iOS Safari tries to load, anyway). All of the files listed in the manifest are valid and served without error.

• The Chrome inspector lists, under "APPLICATION CACHE", all the cached files I've listed which I expect. The entire set of files is about 50 KB, way under any limit on offline resources that I've found.

Is this supposed to work, i.e., am I supposed to be able to create an offline iOS app using only HTML/CSS/JS? And where do I go about figuring out why it's failing to work offline?

(Related but doesn't sound quite the same to me, since it's about Safari and not a standalone app: "Can't get a web app to work offline on iPod")

How to compress/resize image on iPhone OS SDK before uploading to a server?

I'm currently uploading an image to a server using Imgur on iOS with the following code:

NSData* imageData = UIImagePNGRepresentation(image);
NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString* fullPathToFile = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"SBTempImage.png"];
[imageData writeToFile:fullPathToFile atomically:NO];

[uploadRequest setFile:fullPathToFile forKey:@"image"];

The code works fine when run in the simulator and uploading a file from the simulator's photo library because I'm on a fast ethernet connection. However, the same code times out on the iPhone when selecting an image taken with the iPhone. So, I tried it by saving a small image from the web and attempting to upload that, which worked.

This leads me to believe the large images taken by the iPhone are timing out over the somewhat slow 3G network. Is there any way to compress/resize the image from the iPhone before sending it?

Thanks!

using dispatch_sync in Grand Central Dispatch

Can anyone explain with really clear use cases what the purpose of dispatch_sync in GCD is for? I can't understand where and why I would have to use this.

Thanks!

What programming languages can one use to develop iPhone, iPod Touch and iPad (iOS) applications?

What programming languages can one use to develop iPhone, iPod Touch and iPad (iOS) applications?

Also are there plans in the future to expand the amount of programming languages that iOS will support?

AVPlayer and MPMoviePlayerController differences [closed]

I am developing an iPhone application that needs to play videos. So far, I learned that there are at least two API's for achieving this; AVPlayer and MPMoviePlayerController.

What are the main differences?

iPhone UINavigation Issue - nested push animation can result in corrupted navigation bar

I keep getting the following errors:

2011-04-02 14:55:23.350 AppName[42430:207] nested push animation can result in corrupted navigation bar
2011-04-02 14:55:23.352 AppName[42430:207] nested push animation can result in corrupted navigation bar
2011-04-02 14:55:23.729 AppName[42430:207] Finishing up a navigation transition in an unexpected state. Navigation Bar subview tree might get corrupted.
2011-04-02 14:55:23.729 AppName[42430:207] Finishing up a navigation transition in an unexpected state. Navigation Bar subview tree might get corrupted.

Here is what I am doing. From a view controller, I call the following when a certain button is pushed:

EventsViewController *viewController = [[EventsViewController alloc] init];
UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:viewController];
navController.navigationBar.tintColor = [UIColor blackColor];
[self presentModalViewController:navController animated:YES];
[viewController release];
[navController release];

Then, if a certain button is pushed in EventsController, I call:

SingleEventViewController *viewController = [[SingleEventViewController alloc] initWithEvent:[currentEvents objectAtIndex:indexPath.row]];
[self.navigationController pushViewController:viewController animated:YES];
[viewController release];

Then, if a certain button is pushed in SingleEventViewController, I call:

EventMapView* viewController = [[EventMapView alloc] initWithCoordinates];
[[self navigationController] pushViewController:viewController animated:YES];
[viewController release];

So yea, it's obvious that there's nested push animations, but isn't this the right way to go about it? I checked out Apple's DrillDownSave code and this appears to be how they're doing it. Does it matter that I use init methods instead of viewDidLoad methods?