Topic: Creating an iOS wallet for jailbroken devices using BitcoinJ (Read 3428 times)

It looks like Zincwallet might be the way to go. I haven't had the time to try it out though.

https://github.com/voisine/zincwallet

Care to share what you've been doing so far? I've had to put this project on hold for the past few weeks but hope to get going again in a week or so.

You are right! Have some problem with calling into Obj-C to update the GUI. I wish someone would help me as I am not capable to solve it by myself

I don't think playing games like CoG will do any good. Besides, FWIW anything based on bitcoinjs on iOS is going to suck because the JS engine apps get is extremely slow, much slower than the one in mobile safari. The old blockchain.info app used to take several seconds to sign transactions.

I hate when someone out to make a $ releases the same thing... Except closed source.

http://www.coindesk.com/coc-ios-bitcoin-wallet-apple/

I won't be making much progress for the next two weeks - vacation / roadtripping the US.

Anything Bitcoin-related going on in Vegas, Dallas or New Orleans the next few weeks?

https://groups.google.com/forum/?nomobile=true#!topic/robovm/WJp-5byuNPs

That was a bit of a surprise... I will give j2objC a try but I'm pretty sure I'll run into some difficult problems with all the dependencies (+maven).

Yes, things do change. Opinions and decisions can change very fast. Having a wallet around can act like a forcing function anyway - if things do change inside Apple but there's no wallet that can force them to re-evaluate, we might never find out.

I've stumbled on that article as well but I agree with Mike that RoboVM is the obvious choice since it's gone through some serious development since the article. It compiles perfectly and the only exceptions I've encountered were due to my own bad UI code.

I haven't checked out the CoreBitcoin lib though - I take a look later today.

I also doubt Apple will accept wallets any time soon but considering how they suddenly decided to allow real money poker apps (like Pokerstars.com) who knows.

My main reason for trying this is for the millions of nerdy jailbreakers out there - if Apple opens up later then something will be ready and hopefully stable. The adoption potential is huge even when sticking to Cydia distribution.

Hive developer here. I've been thinking about this, but mostly as something for the future, since I think Apple isn't letting wallets back into the App Store anytime soon...

Java dependency is obviously a problem. I found an article comparing some Java-to-iOS tools, but I haven't tried any of these myself: http://www.javaworld.com/article/2078740/java-ios-developer/open-source-java-ios-tools-compared.html

I also found this lib linked on Reddit last week: https://github.com/oleganza/CoreBitcoin - looks promising, but probably not even close to bitcoinj's maturity and stability...

Sure. And if you make a great GUI then it may inspire other people to help you.

Thank you so much!

This project is starting to reach well beyond my skill level on both the objC side and the Java side but a project you really want to succeed seems like a good way to learn

I suppose a simplified process flow will be something like:

1) "Shell" boots up, updates the blockchain, fetches all needed data for the UI, simple "loading..." message etc
2) "Shell" starts the objC UI and feeds it initial data
3) User interaction that requires BitcoinJ (transactions etc.) returns to the Java side and runs transaction logic etc and sends output to the UI (or fails)

For now I think I'll work on prototyping the UI and hopefully I'll figure out how to glue it all together when Niklas Therning has some working examples.

Judging from the RoboVM source, if you can call into Objective-C then you should be able to provide callbacks. Obviously this must be possible, otherwise how would the UIKit bindings work?

https://github.com/robovm/robovm/blob/master/cocoatouch/src/main/java/org/robovm/cocoatouch/uikit/UIActivity.java

From this thread, I see that the devs are working on radically simplifying the boilerplate needed to bind:

https://groups.google.com/forum/m/#!topic/robovm/3ApzrPuQh4M

The new syntax looks a LOT simpler! In particular, note that you can call into Objective-C and pass blocks. So, you would:

1) Have the "shell" be in Java as I guess that's what RoboVM makes easiest. The shell would use WalletAppKit to configure and start up bitcoinj.

2) After that, or in parallel, construct an Objective-C class representing your application GUI. Call methods on it (or set properties) passing blocks into the Obj-C side that it can use to control bitcoinj.

3) Once the UI has all the callbacks it needs, call into a app.run() type method on the Obj-C side, and at that point the Obj-C code takes over and sets up and starts handling the GUI. Button event handlers and the like use the blocks provided earlier to pass control back into Java.

Now, the latest on that thread (from yesterday) is that it doesn't seem to be working yet, though the dev said he wanted to have something by next week. So you could jump on that thread and express your interest along with your use case.

At any rate, it looks like RoboVM is definitely the way to go: it seems to be actively developed and they're making the Java/Obj-C interop a lot cleaner and work better.

For now if you don't want to wait for the auto-binding stuff there's another way. Create two Objective-C (or maybe just plain C?) functions. Init bitcoinj on the Java side as before, then create a Java thread that calls the first GetCommand C function. On the native side, block the thread on a command queue of some kind (i.e. the iOS equivalent of a LinkedBlockingQueue). When it pops something off the queue, it's returned into the Java side as a byte array or struct that represents the "command". The command thread reads the command, converts it into Java calls and manually handles the marshalling back and forth. Once that thread is spun up, call into the second Objective-C function to pass control on the main thread to the native side: this function will return only when the app is about to quit.

In your position I would wait and see what the RoboVM guys come up with. Having their magic compiler generate the marshalling glue for you would be a lot more convenient and result in cleaner code. Whilst you're waiting, you could just mock out a bitcoinj adapter class on the Objective-C side and start work designing your UI.

Yeah, that's my problem at the moment.. I've asked in the RoboVM group. It not too hard to call into objC archive files (.a) but doing the reverse doesn't seem possible. Or maybe I just can't wrap my head around the bridging right.

Here's my(unanswered) question on the RoboVM group: https://groups.google.com/forum/m/#!topic/robovm/WJp-5byuNPs

I've gone as far as considering to compile BitcoinJ as a standalone CLI and interfacing with it that way :/

The Hive guys have managed to bridge it. From the Java side you should be able to call into Obj-C to update the GUI. For calling back, not sure how it works.

Indeed - and hopefully a native client might drag some of the millions of jailbreakers into Bitcoin.

Today I successfully ran the forwardingservice example, downloaded the blockchain etc.

Next step: A viable GUI strategy - it seems writing the GUI logic in objC might be harder than I thought.

I think Apple's ban on Bitcoin clients in their app makes more people to jailbrake thier iPhone as I did to mine.

Successfully compiled and ran "ForwardingService" on the iOS Simulator and got usage text.

Next step: Giving it some arguments...

RoboVM actually looks a lot easier to work with compared to what I was expecting. j2ObjC looks like it can get the job done too, but RoboVM is the obvious choice for now.

I'll absolutely be coding the UI using the native tools in Xcode - that'll make it easier to make the app universal. I hate looking at apps designed for a 4" screen on tablets so I'll try not to make that mistake again.

Thanks again for the tip about RoboVM - hopefully it'll have me running a java "hello world" on the iOS simulator by tomorrow.

Great. Like I said, RoboVM seems like the more mature/well tested solution for iOS at this point.

It has an Objective-C bridge layer, so you can code the UI in Objective-C if you prefer.

Thank you so much for the reply.
The jailbreaker community might be small - but compared to Bitcoin it's HUGE

I'll do what I can to transpile it myself though I doubt I'll succeed on my own. I'll let it be my second pet project for a month or two and hopefully I'll stumble on something.

Please let me know if you (or anyone watching) get into it again,

Thanks,

Anders

The problem with relying on jailbreaking is that Apple is rather good at fixing jailbreaks, and as device security improves they seem to be getting rarer and more complicated over time.

However, if you want to do it anyway then that's great - it would give us a nice wallet ready to go if Apple should ever change their mind, even if the jailbreaker community is rather small!

You could check out this project:

http://www.robovm.org/

It says it can compile Java down to native iOS ARM code. We don't use any fancy tricks like reflection or runtime code synthesis in bitcoinj, partly to help ensure techniques like this can work. Apparently there's a bunch of apps in the app store that use it. Bitcoinj has become quite a large codebase over time, so I'd suggest exploring a bunch of options to make it work on iOS before trying to do a rewrite or anything like that.

The C++ transpiler I was playing with is called j2c. It's quite impressive but needs the native runtime stubs filled out, as it obviously can't compile non-java code to C++. Also it's really just the hobby/prototype project of a (very smart) guy, so don't expect anything in the way of documentation and it required quite a lot of messing around and some bugfixes to get things compiling for me. I never finished the work needed to make a fully native C++ transpile of bitcoinj, but perhaps in future I will revisit this project.

I've found the hivewallet BitcoinKit but it depends on JRE which is a no-go for iOS dev :/
https://github.com/hivewallet/BitcoinKit

What are my options if I want to try to port BitcoinJ a bit more natively?

Let's start off with a quote:

And here's why I strongly disagree:
Apple can only ban what Apple controls. Even though the amount of jailbroken iOS devices is a fraction it is still in the millions... Many millions. And even better: It is the most nerdy fraction of the iOS bunch that are most likely to adopt Bitcoin. It's a huge market, a huge opportunity and a win/win for both the Bitcoin community and the jailbreak community.

I read somewhere that Mike got a library working with OSX/Cocoa.. Has this been abandoned? Can we use it to get started with a working iOS library?
I have a hard time believing that the whole Bitcoin-community is so droidcentric that we will just throw a market in the millions in the trash - it could be huge for Bitcoin if we could get just a small percentage of the jailbreakers to adopt Bitcoin.