Awesome response Nic, I've now just found about UIKitScheduler.
Cheers,
Greg
On 28/05/2012, at 3:56 AM, Nic Wise wrote:
> All of this is IMO, of course :)
>
>> 1. How good is the string/character manipulation performance of MonoTouch in
>> comparison to Objective C? Is it almost as fast?
>>
>
> Should be the same or faster. There may be a very small overhead going
> from a string <-> NSString, but we would be talking nano seconds, I
> suspect. If you are just manipulating strings in your app, not passing
> them to Obj-C code (ie, CocoaTouch) then both should be about the same
> - c#/mono's string handling is, as far as I know, as good as desktop
> .NET (that said you are running on a lower-ghz CPU, so ....)
>
>> 2. How good is the floating point math performance of MonoTouch in
>> comparison to Objective C?
>>
>
> I'd have to let someone from Xamarin answer that, but FP math is built
> into the CPU, I think, so... should be native speeds?? A float is a
> float when you are looking at ARM binary code.
>
> I think MonoTouch can use the SMID stuff on the arm chips, ie the ARM
> equivalent to SSE/MMX ....
>
> Sorry, not something I've had to look into. I suspect it'll be the
> same as Obj-C, unless you are working with data types which are not
> CPU-native.
>
>> 3. My C# program is currently around 500k in filesize. How much would this
>> translate to once it's ported with MonoTouch?
>
> Depends on too many things. Usually, start with 1.5Meg (hello world),
> and go up from there.
>
> you C# app isn't 500k. It's 500k of IL + the .NET framework, which is
> usually about 20meg or so. MonoTouch has to bundle some of that
> framework into the exe, as there is no framework on the phone. the
> linker gets rid of a lot of it tho.
>
> In my current "larger" app (earnestapp.com) the assembles are around
> 2.5meg (IL code - .DLL/.EXE) and the resulting binary is about 8meg.
> On top of that, I have around another 5meg of images and other
> resources, and it zips down to 7meg (ALL apps are sent out and
> submitted to apple as zips - aka IPA's. Look in iTunes, find one, copy
> it, rename to .zip, unzip and have a look)
>
> If it's all non-visual C#, and doesn't pull in a lot of other stuff,
> then I suspect it'll be quite small. But it's very much "how long is a
> piece of string".
>
>>
>> 4. How much of the code would I need to change when using MonoTouch? Apart
>> from GUI stuff, I'm hoping very little. For example, if I have lines like
>> these (unrelated):
>>
>> - CultureInfo.CurrentCulture.TextInfo.ListSeparator
>>
>> - text.Split(new string[] { "TEST" },
>> StringSplitOptions.RemoveEmptyEntries);
>>
>> - Convert.ToDouble(myVar, CultureInfo.InvariantCulture)
>>
>> - (measure)Enum.Parse(typeof(measure), myVar)
>>
>> - Array.Resize(ref ops, i)
>>
>> ....could I use those pieces of code directly, or would they need
>> adjusting for MonoTouch?
>>
>
> I'd say they would work, off the top of my head. Most of the issue is
> around Reflection.Emit, so when you emit some IL and then execute it.
>
>> 5. I use the TimeSpan and DateTime classes. Are these fully supported with
>> MonoTouch?
>
> yes.
>
>> 6. How thorough is the Globalization library and CultureInfo class support?
>> Will MonoTouch recognize the decimal point character etc.?
>>
>
> Yes. And the CocoaTouch ones have very good support for I18N, too,
> baked into the OS. Makes windows look awful (which it is)
>
> I use this, for example:
>
> return CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator;
>
> So that German's get 10,00 and UK gets 10.00
>
>> 7. How is the File class used? Are disc access MonoTouch functions
>> equivalent to their pure C# counterparts? How about a piece of code such as
>> `Application.StartupPath`?
>
> Yes. File works just fine. There are a few restrictions - you can't
> write into your .app folder, but you have a "Documents" folder, a
> "Library" folder and other stuff. The .NET-specific IsolatedStorage
> stuff works find (accross MonoTouch, MonoForAndroid, WP7, Silverlight,
> Win8, Win7 etc)
>
> This might help:
>
> http://docs.xamarin.com/ios/tutorials/Working_with_the_File_System
>
> One thing to note: you really should (must?) use Path.Combine. iOS is
> Unix. Unix is /. Windows is \
>
> This will not work on iOS (at all, ever):
>
> .\Documents\myfile.txt
>
> it has to be
>
> ./Documents/myfile.txt
>
> Path.Combine will get this right based on the OS.
>
>> 8. In C#, the RichTextBox supports Rtf as input. Will MonoTouch allow me to
>> use an equivalent GUI widget which allows Rtf input?
>>
>
> Not as far as I know. The default iOS textbox doesn't do rich text, at
> least as far as I've seen. You'd be writing your own - even if you use
> Obj-C.
>
> iOS has native PDF, which might work if you can convert the RTF to PDF
> if it's for viewing.
>
>> 9. How about HttpWebRequest, WebRequest, and GlobalProxySelection for
>> reading a file from the web?
>
> Yup. All work - I use them. WebClient works too.
>
> Check with Xamarin to see if the Proxy stuff picks up the device proxy
> now. It never used to, but it might do now. I tend to set it in my
> code as needed, tho.
>
> If you use the CocoaTouch native stuff, it all picks up the system
> proxy, but thats also based on a whole different delegate-driven
> model.
>
>>
>> 10. Is threading supported well, including the background worker system?
>
> Yes. you can also use System.Threading.Tasks (which is sweet), as well
> as Thread.QueueWorkItem etc.
>
> Task.Factory.StartNew(() => {
> return "do some stuff on the thread";
> }).ContinueWith(taskResult => {
> Console.WriteLine("oh, I'm on the main thread now!");
> }, new UIKitScheduler())
>
> This is also handy for the UIKitScheduler, which makes sure the
> continuewith is run on the CORRECT UI thread.
>
> https://gist.github.com/1431457
>
>> 11. Are dictionaries fully supported?
>>
>
> You mean System.Collection.Dictionary? and
> System.Collections.Generics.Dictionary<T,U>? Yes. All of
> System.Collections[.Generic] is there.
>
>> 12. And finally, with Monotouch, can I mix C# and objective C code if I
>> wanted to? Or does it all have to be C#?
>
> You can write Obj-C and make it into a library (.a - object file), and
> then link that in. There is a fairly large bunch of bindings on github
> for various things which work like this, including Google Analytics,
> TestFlightapp.com and a load of others. It's not trivial to write at
> first, but it's not overly hard either.
>
> https://github.com/mono/monotouch-bindings
>
> All of these take the published Obj-C output and integrate it into MonoTouch.
>
> Some things to remember:
>
> 1. Your desktop machine is (most likely) a quad or 8 core 3.2Ghz
> machine with 8-16GB RAM and unlimited swap. An iPhone 4S has 512meg
> (1GB?) + 800mhz CPU. And _no_ swap. You can't load a huge document
> into memory and expect it to work!
>
> 2. Get as much off the UI thread (the main thread) as possible. this
> will make your app _feel_ faster, as the animations and the like will
> be smooth, even if the app is taking a while to do something. Async
> programming is pretty much a requirement (you can "not do it" but the
> results are usually kinda awful)
>
> 3. Consider rethinking what your app does. You are (I suspect) moving
> from a 24" screen to a 3.5" one (or 9" for the iPad). Mouse+Keyboard
> -> finger. The same UI paradigms don't port over very well. Consider
> reading Tapworthy by Josh Clark:
> http://shop.oreilly.com/product/0636920001133.do or some other iOS
> design books. I'm not talking about pixel pushing (tho having a full
> time designer is a huge help), but more thinking in the context of the
> user, what they are doing, WHEN and WHERE they are doing it, etc.
>
> 4. Plan the app out on paper before you code a line. Scan the paper in
> and get a feeling for it using the Photos app on the phone. There are
> iOS templates around that you can build realistic wireframe (google
> "Teehan and Lax") or just use pen/graph paper or Balsamiq. You can
> work out a lot of issues cheaply doing this. Briefs is quite good for
> this:
>
> http://giveabrief.com/
>
> (not sure it works anymore tho - Apple pulled it from the appstore, so
> it's a bit manual now)
>
> 5. CocoaTouch is a big API, as is .NET or Windows. Expect it to take a
> little while to learn the ins and outs of how it works. It has a
> different design philosophy to windows or .NET (highly OO, lots of use
> of patterns eg delegate), but it also provides you with a huge amount
> of functions - esp in the UI.
>
> Hope that helps.
>
> Nic
> --
> Nic Wise
> t. +44 7788 592 806 | @fastchicken | http://www.linkedin.com/in/nicwise
> b. http://www.fastchicken.co.nz/
>
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