MonoTouch: creating multiplatform apps using Portable Class Libraries - mono

My scenario: trying to port a small part of an application created by our company from native code (ObjC for iOS / Java for Android) to C-Sharp. The project will interact with our webservices. Goal of this project is figuring out how feasible it is to port our whole app to Mono.
To create URLs, I'd like to use String.Format(). I thought it'd be a wise idea to put this 'service layer' inside a Portable Class Library (PCL) since I don't expect this code to change across platforms. Sadly, it seems the String library is not available for PCLs.
So my question is the following:
I think the main advantage of PCLs over "normal" libraries is that they shouldn't need a recompile for different platforms. Is this assumption correct?
This experience makes me think that for the moment PCLs are rather limited. Should I try to stick with PCLs and work around these kinds of issues, or might it be better to stick with a "normal" library for now? --- I'll assume the "normal" library has more functionality exposed.

You can use PCLs currently across many platforms, but it does require some small hacks to your setup.
These hacks are listed in http://slodge.blogspot.co.uk/2012/12/cross-platform-winrt-monodroid.html
Once you've got those working then the functionality available is quite broad - and it definitely includes things like String.Format
For the situations where the PCL profile is not broad enough, then you can use several techniques for extending them - see http://blogs.msdn.com/b/dsplaisted/archive/2012/08/27/how-to-make-portable-class-libraries-work-for-you.aspx . The technique I generally use is to use MvvmCross Plugins - which are basically PCL interfaces with platform specific implementations. But these plugins are generally at the level of 'make bluetooth work' rather than at the level of String.Format
I do lots of PCL work across WinRT, WP, WPF, MonoTouch and Mono for Android - see http://slodge.blogspot.co.uk/p/mvvmcross-quicklist.html for lots of links to PCL work.
It's true that Xamarin have recommended not using PCLs for a couple of years, but that situation has now changed and the official support for PCLs is under way - see http://slodge.blogspot.co.uk/2013/02/the-future-is-portable.html
From a development perspective - especially from the point of view of using refactoring and testing tools - I don't hesitate to recommend you use PCLs now... especially for operations at the String.Format level. However, each project is unique... so it's not always the right answer.
One important note: right now it's better to not reuse the PCL binary files across to the MonoTouch platform - for now, build your portable libraries against the specific MonoTouch library platform. See http://slodge.blogspot.co.uk/2013/01/almost-portable-binaries.html?m=1

Perhaps you want to look at the efforts other who have got PCLs working to a considerable degree with monotouch and monodroid.
For example see http://www.slideshare.net/cirrious/mvvm-cross-going-portable . You'll also find instructions on how to setup PCL support for MVVMCross here http://slodge.blogspot.co.uk/2012/09/mvvmcross-vnext-portable-class.html .
Xamarin has recently committed to providing far greater PCL support rather than some of the workarounds that people have been having to make, but it is worth the effort.

Related

Generate Objective-C code from any other language

Are there frameworks/generators for producing iOS code from any other language?
A dynamic language like JavaScript, ruby or Python are preferred. Googling for iOS code generators was largely fruitless.
The problem with systems like PhoneGap is that their output is a full-fledged application. What I need to produce is a library (.a & .h file eventually) that other Objective-C developers can reuse in their projects.
RubyMotion may or may not do what you want. I haven't seen much about the practicalities of it yet, but I'm thinking since it's statically compiled chances are good that it can produce libraries that can be simply linked into Objective-C projects. One might need another tool to produce the header files.
Of course, this is all speculation.
I think the best solution for what you're looking for is Titanium. It has its own sdk (in JavaScript), a complete IDE and allows you to have one codebase for all major platforms (iOS, Android included). What it's really awesome is the fact that it actually generates native code (a valid XCode project or a Java one for Android). It's also free and open source. Definetely worth a look.
I've never seen code generators, but there are a variety of "spoofs" as it were.
http://xamarin.com/monotouch - iOS on C#
http://phonegap.com/ - iOS on HTML, CSS , Javascript
http://ipodtoucher55.blogspot.com/2010/06/how-to-create-iphone-apps-in-flash-cs5.html - one of several tutorials for flash on iOS
I've seen links to python libraries and I think java too.
When it comes down to it though, they're all work arounds, not direct development.

guidelines for developing a small Mac OSX project

I'm a .NET developer with some questions about a small Mac project coming up.
We are going to be creating a small program for Mac OSX. The software will need to have a simple UI (1 screen) and will need to consume a WCF web service.
Should we code on our Windows boxes or on Mac machines? We have a couple Mac Minis, but we mostly do Windows development.
What IDE/dev environment should we use? (Eclipse, Xcode, etc.)
How does Mac software deployment generally work?
...
No one has mentioned Java/Eclipse. Isn't that an option?
Here are two options:
Write in Objective-C, using Xcode on Macs
Write in C#, using Mono on Windows or on a Mac with SharpDevelop
The advantage of #1 is the resulting app will be much easier to deploy to others, but you might have trouble consuming the WCF service. It depends on what exact interface you are exposing and what the types of the parameters are.
The advantage of #2 is that you can use your C# skills. I don't know the state of WCF in Mono, and the GUI may not look native.
If you go with #1, the main issue will be using Objective-C. Since you are targeting the Mac, make sure you enable the Garbage Collector, or else you will have to also learn memory-management. If you use Xcode 4, it's similar in spirit to Visual Studio, although the details are different. For a simple project, following the tutorials will probably be enough -- I suspect the hard part will be interacting with WCF. To make your life easier, make the interface to the service extremely simple (simple parameter types and returns).
Your question is overly broad. You have two options:
When in Rome...: download Xcode, look at example apps, read Apple's documentation, find some tutorials, and learn Mac app development the usual way.
The Devil You Know...: look into stuff like the Mono project that will let you write a Mac app in C#, so you can use your existing libraries and don't have to learn Objective-C.
Which is better depends on your needs. If you just want to get a small app done and don't have a lot of time/money, I'd go with #2. If you're concerned about quality (compatibility libraries always have their quirks), I'd go with #1. My gut says #2 is better for you.

How hard is it for a .NET programmer to learn Objective C and Cocoa?

I'm trying to build a dual platform application for a company of my own I'm trying to start at night.
I have the .NET version done, but have not finished the UI part. I'm thinking of buying some 3rd party controls.
If I buy these controls, however, they clearly will only work in my Windows version. I'm wondering if I should try to do the UI in GTK# and use Mono with CocoaSharp or just build the thing in MS technology and teach myself the Mac side?
I'm just really unfamiliar with the Mac world and am wondering how much of a learning curve there might be.
I've thought perhaps of rewriting my core logic in Ruby or Python. This why I could use the .NET version with .NET controls and presumably hook the same code up on the Mac.
It's an educational app targeted at consumers. As such, it shouldn't require a lot of technical sophistication to install.
If the non-visual part of the .NET application is quite big compared to the UI, then you can go full .NET and adopt the following two-steps strategy:
Non-Visual Part
Develop the non-visual .NET part to be the most platform independent.
Platform dependent code for non-visual code should be isolated in small classes that provide the same interface so they could be plugged according to the platform.
User Interface
Use System.Windows.Forms (or your favorite toolkit) for Windows
Use a Cocoa bridge (see this page for the choices) for Mac OS X.
You still can benefit from learning Objective-C: as the Cocoa bridges are usually heavily based on the Apple's API, you will find a lot of help in the Apple's sample code (which are in Objective-C).
On Windows, the application will run with the Microsoft .NET runtime and on Mac OS X, the application will run with the Mono runtime.
The DeepMeta application uses this strategy. As you can see the user experience is quite good on both platforms.
Avoid using cross platform UI tools; the result will never be as good as a native implementation, which is especially bad on the OS X where most customers expect a certain level of polish in their applications. Implementing the core logic in a platform independent language like C++ and maintaining a different code base for the interface on each platform can be a good solution, especially if you have a very complex model.
Anyway, you shouldn't have too much difficulty learning Cocoa if you're a good .NET programmer; I did the reverse several years ago and didn't have much trouble. Objective-C is more C oriented than C#, but if you know the basics about pointers and such you're going to be okay. Cocoa and .NET definitely have their differences in certain areas, but they're both high level frameworks which you shouldn't have too much trouble understanding. Get a good book (Hillegass is the go-to author) and go through it so you understand how the two APIs use different design patterns in certain areas, and don't try to fight the framework if it's different than what you're used to.
In my experience this will make you a better programmer in the long run by expanding your knowledge, even if you don't write any more Cocoa applications.

Sharing logic across different platforms

We have a business logic that works with the file systems on OS that we want to implement on both Linux and Windows platforms. The language we have selected is Python for Linux and C# for Windows. GUI is not a priority for now. We were looking for ways to abstract the business logic in a way that we dont have to repeat the business logic (ofcourse I understand since it is related to file system, some code will differ from platform to platform).
Any ideas on how to implement it? Is C/C++ the only option. We dont want to use Java.
Thanks,
Pranz
yea, pick a common language for the logic first. Punting down in to C/C++ pretty much eliminates any of the real values to development that the Python and C# languages provide. Done write, MOST of your logic will be "Business Logic" with the rest glue to external services (i.e. databases, etc.).
So, you should pick a portable environment from the get go. Dropping down to C/C++ and linking it in is a viable alternative, but most likely not worth the time.
Mono is an option you'll probably want to look into.
Quote from the site for easy explanation:
Mono is a software platform designed to allow developers to easily create cross platform applications. Sponsored by Novell, Mono is an open source implementation of Microsoft's .NET Framework based on the ECMA standards for C# and the Common Language Runtime. A growing family of solutions and an active and enthusiastic contributing community is helping position Mono to become the leading choice for development of Linux applications.
Either use Mono or Python.
Mono allows you to run C# .NET code on both platforms. Python can be executed on both platforms already.
Qt has cross-platform libraries for all sorts of things, including UI and file system. It does, however, use C++.

Qt4.5 vs Cocoa for native Mac UI

I've been developing for Windows and *nix platforms for quite some time, and am looking to move into Mac development. I am tossing up between using ObjC/Cocoa and C++/Qt4.5.
The C++/moc semantics make more sense to me, and improving knowledge in Qt seems like a sensible thing to do given that you end up with a skill set that covers more platforms.
Am I likely to handicap my applications by skipping Cocoa?
The sample Qt applications look pretty Mac-native to me, but they are quite simple so potentially don't tell the whole story. Are there other pros to the Xcode way that Qt doesn't have, such as packaging, deployment, etc.?
Here's an easy way to answer it:
If you were developing a Windows app with .NET or MFC, would you handicap your applications by using Qt? If the answer to that is yes, then the situation is likely to be the same on the Mac.
A few negatives I can think of off the top of my head:
Licensing
Qt apps, while good, are not completely a native UI experience and there's things a native UI designer can do in Cocoa which boggle the mind. While I can't be sure that all the same functionality isn't available in Qt, I doubt it.
Qt is always a little behind. If Microsoft or Apple come out with a great new technology, you have to wait for the Qt developers to update Qt.
However, with all that said, only you can determine the business value of using Qt. If you think cross-platform development is going to be a major part of your development, then Qt might be worth it, despite the issues mentioned.
Ask yourself: how many of the best Mac applications that you know of use Qt instead of native Cocoa?
For our robotic systems, we originally wrote our control software in C++ using the cross-platform wxWidgets library (we avoided Qt due to some licensing concerns), because we felt that we had to target Windows, Linux, and Mac platforms for our end users. This is what we shipped for over a year until I started tinkering with Cocoa.
Right away, the thing that most impressed me was how quickly you could develop using Cocoa. Eventually, we decided to drop support for Linux and Windows and rewrite our entire control applications in Cocoa. What had taken us years to put together in C++ required only three months to completely reimplement in Cocoa.
Aside from the "lowest common denominator" interface issues that others have pointed out, the rapid development allowed by Cocoa has become a competitive advantage for our company. Our software has advanced far more quickly since our conversion to Cocoa, and it has allowed us as a new company with one developer to pull even with 10-year-old competitors that have 20-man development teams. This appears to be a common story in the Mac development space, where you see a lot of small teams who are able to create products that compete with those of much larger companies.
As a final note, using Cocoa gives you the ability to stay on top of the new APIs Apple is continually rolling out. We're now working on a new control interface that will make heavy use of Core Animation, something that would be painful to deal with using Qt.
I'm currently developing both with QT (actually PyQT, but it makes no difference to your question) and native Cocoa app. For me it's no brainer, I'd chose Cocoa. It's really worth time to explore Cocoa in general, there are many great concepts within the Cocoa framework, and Objective-C 2.0 as well.
I'd use Qt if you want this to be a crossplatform application.
You can have a look at the QMacCocoaViewContainer class. It acts as some kind of wrapper for generic Cocoa views, so you can also have Cocoa elements which are not officially supported by Qt.
Of course this means learning a little about Cocoa and Objective C and how a Cocoa UI would need to look like. But if you already know Qt well and if it’s not like your application is all and only about the GUI this could be a good way to go.
And don’t forget about the QMacStyle::WidgetSizePolicy or you won’t understand why your tables come out so huge.
Obviously, the best option is to use a cross platform suite that supports native widgets.
With QT4 you can build your base user interface. Then just add native support for your specific target platform.
Sure, Cocoa has a lot of fancy stuff (and you can still use them trough QT4), but let me be clear. I see a lot of fancy Apps on the AppStore, pretty ones, but most of then are just crap, expensive.. what ever. I really missed my Kate text editor, my okular viewer, my krita drawing software... those are just better than the commercial and expensive alternatives and are free. so i just tweak the source code a little bit too have a REAL native and great experience.
What if i have to use a linux app on my main computer with is a mac os x? or windows? or whatever? only?
For example, why on earth i have to buy a expensive ,fancy but far less featured image editor software for my mac like pixelmator when i can use a full featured real image manipulation software like Gimp? YES Gimp is gtk2 based which is a pain on any platform, specially on Mac because is really ugly. Gimp should be ported to QT4. Inkscape should be ported to QT4 too, and it would feel so great.
Is so simple to do.. gosh!
http://doc.qt.nokia.com/4.7-snapshot/demos-macmainwindow.html
Even you can add support for the the new native lion fullscreen feature, unified title and toolbar menus, etc
I , as a user, i really care about efficient, featured, good and cross platform apps, i don't really care about developer's convenience or laziness .
I do a lot of cross-platform development (Mac, Windows, Linux), and for some projects use Qt. It is a fine framework, and provides a rich class library. If you need to deploy on multiple platforms, cannot afford to spend the time/effort on platform-specific front-ends, or the "generic" support for each platform is sufficiently good, then use Qt.
However, Qt inevitably suffers in some ways from the lowest common denominator syndrome, and sometimes does not feel quite native enough. There are also certain features that are either difficult to support, or are simply not provided in the Qt libraries. So if you can afford the time and effort, or your app really demands the attention to detail and fit & finish, then developing separate front-ends may be worth it.
In either case, you ought to be writing your back-end (aka domain) code in a platform-neutral and front-end neutral manner. This way, the front-end is easily replaced, or modified between platforms.
You could always start with a Qt front-end and go for a quick time to market, then develop a native front-end down the line.
In practice, I've noticed that a Qt app on Windows looks most "native", while on Mac there are certain subtle telltale signs that make it look/feel not quite right. And Mac users tend to have much higher expectations when it comes to UI/UX!
Since posting this, i've been learning the Cocoa / Objective-C way, and have been quite impressed. Despite what I initially thought was quite a quirky syntax, Objc appears to be a very effective language for implementing UI code, and the XCode sugar - things like Core Data and bindings - make short work of all of the boring bits.
I spent a while with the QT examples and documentation before digging into cocoa, and tend to agree with what has been said above w.r.t being slightly behind the curve and less 'aqua-ish' - albeit from a fairly trivial inspection. If I absolutely had to be build a cross-platform app i'd probably use QT rather than trying to separate out the UI code, as it seems like it would provide close-enough visuals, but for mac only purposes, Cocoa seems like a definite win.
Thanks all for your responses, they've all been very helpful!
DO NOT use Qt for a Mac app. You will get no hardware acceleration for 2D rendering, and you will not be able to deliver ADA compliance.
Depending on what kind of apps you want to write, another contender is REALbasic now called Xojo.
The move from C++ is pretty easy (I have 15 years C++ experience) and the framework and IDE extremely productive. You have the added bonus of being able to deploy to Linux and Windows with trivial effort. Their framework compiles to native code and uses native widgets so you don't have an emulated look and feel.
The big reason for learning Cocoa and coding in Objective-C is if you want to hone your iPhone skills or are chasing a really fancy user experience. If you wanted to rival the cutting edge of WPF development then I'd recommend Cocoa.