Compiling iOS applications on-device: Difference between revisions

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This article will be useful to anyone that does not have a Mac to compile apps or does not want to pay the $100/year fee to run code on your own device.
This article will be useful to anyone that does not have or want to buy a Mac to compile apps or does not want to pay the $100/year fee to run code on your own device.


You don't even need a secondary desktop or a laptop to do this! However it is not recommended to actually code the app directly on-device, unless if you're a masochist or something.
You don't even need a secondary desktop or a laptop to do this! However it is not recommended to actually code the app directly on-device, unless if you're a masochist or something.

Revision as of 01:43, 3 December 2014

This article will be useful to anyone that does not have or want to buy a Mac to compile apps or does not want to pay the $100/year fee to run code on your own device.

You don't even need a secondary desktop or a laptop to do this! However it is not recommended to actually code the app directly on-device, unless if you're a masochist or something.

By design this tutorial does not require the usage of third party frameworks such as Theos, the idea of this tutorial is to get people to understand how iOS applications are built and run behind the scenes.

Prerequisites

Aquire an iOS device with iOS 5 or higher and jailbreak it.

This technically could work with lower iOS versions, but the available toolchain on Cydia was compiled for iOS 5.

Install the toolchain

Open Cydia and install these:

  • Tape archive
  • iOS toolchain
  • OpenSSH
  • wget

Or just run

apt-get install tar org.coolstar.iostoolchain openssh wget

as root (default password: alpine).

Get the SDK

They are found here: http://iphone.howett.net/sdks/

You can literally use any SDK you want as long as they have the frameworks you need, however it is recommended you use the iOS 7 SDK or higher as the lower ones do not support arm64 (optimized for iPhone 5s and higher).

Right click "Download" on one of the SDKs and copy the link.

SSH into your device (user: root or mobile, default password: alpine) and run these commands:

cd /var
mkdir sdks
cd sdks
wget http://iphone.howett.net/sdks/dl/iPhoneOS8.1.sdk.tbz2 #or whatever SDK you wanted
tar xvf iPhoneOS8.1.sdk.tbz2
rm iPhoneOS8.1.sdk.tbz2
ln -s iPhoneOS8.1.sdk Latest.sdk

Boom. Your device can now compile iOS applications.

Creating a vanilla app

Creating the app structure

Run these commands (as root, default password alpine):

cd /Applications
mkdir Test.app
cd Test.app
touch Test
chmod +x Test

Then create a file Info.plist in /Applications/Test.app/ with the following contents:

<dict>
    <key>CFBundleExecutable</key>
    <string>Test</string>

    <key>CFBundleIdentifier</key>
    <string>net.iphonedevwiki.test</string>

    <key>CFBundleName</key>
    <string>LOL</string>

</dict>

Then login as mobile (default password alpine) and run:

uicache

If you did everything right, once the command is done running you should see this on your homescreen:

32b04b5cf33cd6f4790d106e3defc533.png (On iOS 6 and lower, there would be no lines in the white square)

When you try to open the app, it will crash! That's because you actually haven't written anything yet.

Actually writing a working app

This will not be the best written app in the world but it will have enough explanation for you to understand what you need to do if you want multiple files.

Make a folder in /var/mobile called test_app_src (or something, just somewhere to hold your code).

Change directory into this folder and make 3 files: main.m, TestLabel.h, and TestLabel.m.

main.m

#import <UIKit/UIKit.h>
#import "TestLabel.h"

@interface TestAppDelegate : UIResponder <UIApplicationDelegate>
@property (nonatomic, strong) UIWindow *window;
@end

int main(int argc, char *argv[])
{
    @autoreleasepool
    {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass(TestAppDelegate.class));
    }
    return 0;
}

@implementation TestAppDelegate
@synthesize window=_window;

-(BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [UIWindow.alloc initWithFrame:UIScreen.mainScreen.bounds];
    self.window.backgroundColor = UIColor.redColor;

    UILabel *label = [[TestLabel alloc] initWithBackgroundColor:self.window.backgroundColor];
    [self.window addSubview:label];
    [label release];

    [self.window makeKeyAndVisible];

    return true;
}

@end

TestLabel.h

#import <UIKit/UIKit.h>

@interface TestLabel : UILabel
-(instancetype)initWithBackgroundColor:(UIColor *)backgroundColor;
@end

TestLabel.m

#import "TestLabel.h"

@implementation TestLabel
-(instancetype)initWithBackgroundColor:(UIColor *)backgroundColor
{
    if(self == [self init])
    {
        self.backgroundColor = backgroundColor;
        self.textColor = UIColor.whiteColor;
        self.text = @"rofl";
        self.frame = CGRectMake(20,20,300,300);
    }
    return self;
}
@end

Compiling

Run these commands:

clang -isysroot /var/sdks/Latest.sdk \
      -c main.m
clang -isysroot /var/sdks/Latest.sdk \
      -c TestLabel.m
clang -isysroot /var/sdks/Latest.sdk \
       -framework Foundation \
       -framework UIKit \
       main.o TestLabel.o \
       -o Test

Installing

If you didn't get any errors, when you list the contents of the directory with your code in it you should see this:

main.m TestLabel.m TestLabel.h main.o TestLabel.o Test

Copy Test into /Applications/Test.app/ and overwrite the old empty Test file you created earlier.

Then, go ahead and open the app again and you should see this:

Error creating thumbnail: File missing

WAU, that AMAZING!!!1!

Other details

Using other frameworks

For example, if you wanted to use AVFoundation, add the -framework AVFoundation flag during the last compile step (similar to how I used -framework UIKit and -framework Foundation).

Removing the black letterboxing on 4-inch devices

To get the app to use the entire screen real-estate you need to add a the file [email protected] to /Applications/Test.app/. The file needs to be 640x1136 pixels. Instead of creating it yourself, you could just copy it in from another application (like /Applications/Cydia/[email protected]).

You will also need to run uicache again as mobile in order to see these changes take effect.

Enabling automatic reference counting (ARC)

Add the -fobjc-arc flag when compiling.

Icons, default backgrounds, entitlements, iPad compatibility, etc

Check out Apple's documentation on the subject. You can also look in any of the other Info.plists in the /Applications/ directory on your device! Cydia.app would be a good place to start.

Every change to Info.plist or the application's icons must be followed by the command uicache as mobile in order to see changes take effect.

Uninstalling

Delete it from /Applications/ and run uicache as mobile again. iOS thinks it's a system app, so you can't delete it like a normal iOS app.

Getting it on the App Store

lol