How to Transfer Files from One Application to Another in the Same iOS Device

How can I transfer files from one application to another in the same iOS device?

UIDocumentInteractionController is your friend.

Basically it works like this:

App 1 registers as being able to handle files of type XYZ
App 2 implements UIDocumentInteractionController and will give users the options to "send the file to App1" (I believe this has to be user activated)
App 1 implements -(BOOL)application:openURL:sourceApplication:annotation: and deals with the transferred file which will be saved in your Documents/Inbox directory. From there you can copy the file elsewhere and then manipulated it, making sure you clean up by getting rid of the original one saved on the Inbox folder.

Class reference available here

Document interaction programming guide available here

How to transfer data from one app to another app in same ios device?

There's an example of UIDocumentInteractionController to share files on iOS. iOS is designed to prevent apps from sharing data directly. So, UIDocumentInteractionController provided by Apple is the thing you should use to mimic something similar to direct sharing.

-(void)shareOnInstagram:(UIImage*)image {

    NSString  *jpgPath = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/image.igo"];
    [[NSFileManager defaultManager] removeItemAtPath:jpgPath error:nil];
    [UIImageJPEGRepresentation(image, 0.6) writeToFile:jpgPath atomically:YES];

    NSURL *igImageHookFile = [NSURL fileURLWithPath:jpgPath];
    self.dic = [self setupControllerWithURL:igImageHookFile usingDelegate:self];
    self.dic.UTI = @"com.instagram.exclusivegram";
    [self.dic presentOpenInMenuFromRect:CGRectMake(0, 0, 320, [UIScreen mainScreen].bounds.size.height) inView:self.view animated:YES];
}

- (UIDocumentInteractionController *) setupControllerWithURL: (NSURL*) fileURL usingDelegate: (id <UIDocumentInteractionControllerDelegate>) interactionDelegate {
    UIDocumentInteractionController *interactionController = [UIDocumentInteractionController interactionControllerWithURL: fileURL];
    interactionController.delegate = interactionDelegate;
    return interactionController;
}

See https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIDocumentInteractionController_class/

How to transfer data from one app to another app from different iOS devices which have same WiFi network in swift?

I used MultipeerConnectivity framework and it works great

Transfer file from one ios device to another using wifi and 3G network?

To do transfers between two devices without a mediator, at least one device must run some kind of a server (like http://code.google.com/p/ios-ftp-server/, for the client see SimpleFTPSample). But then you also need to discover ip addresses (maybe with ZeroConf). A lot of hassel, if possible at all; both clients must be in the same network and therefor won't work on 3G.

If you are ok with a mediator, things get much simpler. I have created an Open Souce App called cross copy which uses http REST commands to transfer files between devices (and hence also provides a web app for the desktop).
Obviously there are other nice mediator-based solutions: DropBox, Bump, Hoccer, etc

Share Files between Apps on the same iPad (Without iCloud)

This link at github may be useful... Looks like someone has already made a file manager, using these elements you may be able to do what you are looking for. But as far as I know, your app is extremely sandboxed and does not really interact with other apps/the file system very much at all (Apple is very limiting that way)

EDIT

this post seems to have the explanations of local data sharing methods you were looking for. None of the methods in this post requires any connectivity, just a device and 2 apps :) Good luck!

Access files of one Application from other application in ios

Read Apple Doc File System Basics

How to share files with all other devices from my iOS device through application?

iBeacon is not for file sharing, for more information check this link

And about file sharing between Android and iOS via Bluetooth it has asked before here

But you can write an App that enables file sharing between iOS devices quite simple. Check MultiPeer Connectivity Framework

Also there are new technologies but I don't have enough information about them.