What's new in Xamarin.iOS, by Miguel de Icaza
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This document provides a summary of new features in Xamarin.iOS, including: 1. Features based on Mono 3.0 including a Mono 3.0-based stack, SGen GC, and .NET 4.5 API surface. 2. Size reductions through features like SmartLink, which only includes referenced code, reducing app sizes by up to hundreds of kilobytes. 3. Runtime improvements such as generic value type sharing to reduce errors and enable more generic-rich apps to run without changes. 4. Debugging aids like NSObject.Description and UIApplication.CheckForIllegalCrossThreadCalls to help write threaded apps. 5. Async support with async versions of
![Thread Safe APIs
Thread Safe Classes
• UIColor
• UIDocument
• UIFont
• UIImage
• UIBezierPath
• UIDevice
Key Thread Safe Methods
• UIApplication.SharedApplica
tion, Background APIs
• UIView.Draw
See API docs for
[ThreadSafe] attribute
Released](https://image.slidesharecdn.com/miguelevolve-newios-130514133512-phpapp02/85/What-s-new-in-Xamarin-iOS-by-Miguel-de-Icaza-26-320.jpg)
![UIGestureRecognizers
Before
void Setup ()
{
var pan= new UIPanGestureRecognizer (
this, new Selector (”panHandler"));
view.AddGestureRecognizer (pan);
}
[Export(”panHandler")]
void PanImage (UIPanGestureRecognizer rec)
{
// handle pan
}
Problems:
• Error prone: Parameter of PanImage must be right type
• No checking (mismatch in selector names)
Now
void Setup ()
{
var pan = new UIPanGestureRecognizer (PanImage);
view.AddGestureRecognizer (pan);
}
void PanImage (UIPanGestureRecognizer rec)
{
// handle pan
}
Pros:
• Compiler enforced types
• No selectors to deal with
Released](https://image.slidesharecdn.com/miguelevolve-newios-130514133512-phpapp02/85/What-s-new-in-Xamarin-iOS-by-Miguel-de-Icaza-34-320.jpg)
What's new in Xamarin.iOS, by Miguel de Icaza
- 1. What is new on Xamarin.iOS Xamarin Inc
- 2. New in Xamarin.iOS • Features added in the last year – Based on the Mono 2.10/Silverlight-ish stack • Features based on the Beta channel: – Mono 3.0-based stack – SGen GC – Based on the .NET 4.5 API surface Released Beta
- 4. F# Support • Functional Programming comes to iOS! • The pitch is simple: – Fewer bugs – Focus on intent – Reuse C# libraries, experience – More features, less time Beta
- 6. TweetStation – Reference App • Comprehensive app • Networking • SQL • Background • Retina artwork • Full (unlinked) MonoTouch.Dialog
- 7. TweetStation Size Reduction 6,200 6,400 6,600 6,800 7,000 7,200 7,400 7,600 4.2.2 5.0.4 5.2.13 5.4.1 6.0.10 iOS 6 6.2.1 6.3.3.2 Async (Mono3) Size in KB Size in KB Released
- 8. New: SmartLink • By default, all native code is linked-in • SmartLink merges Mono and System linker – Only code that is directly referenced is included – Caveat: dynamic Objective-C code can fail – Big savings: Beta
- 9. SmartLink effect on Samples - 2,000 4,000 6,000 All code Smart Linking Beta
- 12. Generic Value Type Sharing • Reduces these kinds of errors: Unhandled Exception: System.ExecutionEngineException: Attempting to JIT compile method • By generating generics code that can be shared across value types – like reference types today • Enables more LINQ, RX and other generic-rich apps to run without changes, or without manual static stubs Beta
- 13. Source of the Error • Static compiler is unable to infer that certain generic methods will be used at runtime with a specific value type. • Because the instantiations are delayed until runtime. Beta
- 14. Generic Sharing • Consider: List<T>.Add (T x) • If “T” is a reference type: – Code can be shared between all reference types – Only one List<RefType>.Add (RefType x) exists – Because all reference types use same storage (one pointer). Beta
- 15. Generics and Value Types • Value types use different storage: – byte – 1 byte – int – 4 bytes – long – 8 bytes • List<byte>.Add (byte x) has different code than List<long>.Add (long x) Beta
- 16. Generic Sharing Today • Using string, Uri, object, int, long on Add: – Generates one shareable for Uri, object, string – Generates one for int – Generates one for long
- 17. With new Generic Value Type Sharing • Using string, Uri, object, int, long on Add: – Generates one shareable for Uri, object, string – Generates one for int – Generates one for long – Generates a value-type shareable • Can be used by dynamic users of Add<ValueType> Beta
- 18. Shareable Value Type Generic • Runtime fallback for generic instantiations that could not be statically computed • Uses a “fat” value type • Generates code that copies “fat” value types • Limitation: large value types can not be shared • You can disable if not needed: – -O=-gsharedvt Beta
- 19. Cost of Value Type Sharing 6,200 6,400 6,600 6,800 7,000 7,200 7,400 7,600 4.2.2 5.0.4 5.2.13 5.4.1 6.0.10 iOS 6 6.2.1 6.3.3.2 Async (Mono3) VT Sharing Size in KB Size in KB 394 Kb Today: For TweetStation, the cost is 394kb We are working to reduce this Beta
- 20. Native Crypto • System.Security.Cryptography now powered by iOS native CommonCrytpo • Covers – Symmetric crypto – Hash functions • Hardware accelerated – AES and SHA1 (when plugged) • Made binaries using crypto/https 100k lighter Released
- 21. SGen • SGen can now be used in production on iOS • It is no longer slower than Boehm • And much faster on most scenarios Beta
- 22. DEBUGGING AIDS
- 23. NSObject.Description • New API that provides Objective-C “ToString” • NSObject.ToString() calls Description • Sometimes overwritten – You can always call NSObject.Description Released
- 24. Helping you write Threaded Apps • UIKit is not thread safe – No major commercial UI toolkit is thread safe – Thread safety is just too hard for toolkits • Very few UIKit methods are thread safe • During debug mode, you get an exception Released
- 25. UIApplication.CheckForIllegalCrossThreadCalls • If set, accessing UI elements – Throws UIKitThreadAccessException • Most UIKit classes/methods • UIViewController implemented outside UIKit • Checks enabled on Debug, disabled on Release builds – Force use: --force-thread-check – Force removal: --disable-thread-check Released
- 26. Thread Safe APIs Thread Safe Classes • UIColor • UIDocument • UIFont • UIImage • UIBezierPath • UIDevice Key Thread Safe Methods • UIApplication.SharedApplica tion, Background APIs • UIView.Draw See API docs for [ThreadSafe] attribute Released
- 27. ASYNC
- 28. Async Support • Base Class Libraries: – Expect all the standard Async APIs from .NET BCL – Coverage is .NET 4.5 Complete for BCL • MonoTouch specific: • 114 methods on the beta • Easy to turn ObjC methods into Async ones – Details on the Objective-C bindings talk Beta
- 29. Async Synchronization Contexts • For UI thread, we run a UIKit Sync Context – What you get from the main thread – Code resumes execution on UIKit thread – Using async just works – Transparent • Grand Central Dispatch Sync Context – If you are running on a GCD DispatchQueue – Will resume/queue execution on the current queue Beta
- 30. General Async Pattern • Methods with the signature: void Operation (…, Callback onCompletion) • Become: Task OperationAsync (…) Beta
- 31. API IMPROVEMENTS
- 32. More Strong Type Constructors • Where you saw – NSDictionary options • We now support strongly typed overloads – Give preference to strongly typed overloads – Reduce errors – Trips to the documentation – Unintended effects Released
- 33. Screen Capture • To capture UIKit views: – UIScreen.Capture () • To capture OpenGL content: – iPhoneOSGameView.Capture () Released
- 34. UIGestureRecognizers Before void Setup () { var pan= new UIPanGestureRecognizer ( this, new Selector (”panHandler")); view.AddGestureRecognizer (pan); } [Export(”panHandler")] void PanImage (UIPanGestureRecognizer rec) { // handle pan } Problems: • Error prone: Parameter of PanImage must be right type • No checking (mismatch in selector names) Now void Setup () { var pan = new UIPanGestureRecognizer (PanImage); view.AddGestureRecognizer (pan); } void PanImage (UIPanGestureRecognizer rec) { // handle pan } Pros: • Compiler enforced types • No selectors to deal with Released
- 35. UIAppearance • Previously: var appearance = CustomSlider.Appearance; appearance.SetMaxTrackImage (maxImage, UIControlState.Normal); – Problem: does not work for subclasses • Now: var appearance = CustomSlider.GetAppearance<CustomSlider> (); appearance.SetMaxTrackImage (maxImage, UIControlState.Normal); Released
- 36. Notifications • Used in iOS/OSX to broadcast messages – Untyped registration – Notification payload is an untyped NSDictionary • Typically require a trip to the docs: – To find out which notifications exist – To find what keys exist in the dictionary payload – To find out the types of the values in dictionary Released
- 37. Xamarin.iOS Notifications • Discoverable, nested “Notifications class” • For example: UIKeyboard.Notifications • Pattern: – Static method ObserveXXX – Returns observer token – Calling Dispose() on observer unregisters interest Released
- 38. Example – Full Code Completion notification = UIKeyboard.Notifications.ObserveDidShow ((sender, args) => { // Access strongly typed args Console.WriteLine ("Notification: {0}", args.Notification); // RectangleF values Console.WriteLine ("FrameBegin", args.FrameBegin); Console.WriteLine ("FrameEnd", args.FrameEnd); // double Console.WriteLine ("AnimationDuration", args.AnimationDuration); // UIViewAnimationCurve Console.WriteLine ("AnimationCurve", args.AnimationCurve); }); // To stop listening: notification.Dispose (); Released
- 39. NSAttributedString • On iOS 5: – Introduced for use in CoreText • On iOS 6: – It became ubiquitous on UIKit – UIKit views use it everywhere • Cumbersome to create Released
- 40. NSAttributedString • Standard Objective-C esque approach: // // This example shows how to create an NSAttributedString for // use with UIKit using NSDictionaries // var dict = new NSMutableDictionary () { { NSAttributedString.FontAttributeName, UIFont.FromName ("HoeflerText-Regular", 24.0f), }, { NSAttributedString.ForegroundColorAttributeName, UIColor.Black } }; • Error prone: – Get right values for keys – Get right types for values – Requires documentation trips Released
- 41. NSAttributedString – C# 4 style var text = new NSAttributedString ( "Hello, World", font: UIFont.FromName ("HoeflerText-Regular", 24.0f), foregroundColor: UIColor.Red); • Uses C# named parameters • Uses C# optional parameter processing • Use as many (or few) as you want Released
- 42. AudioToolbox, AudioUnit, CoreMidi • Completed MIDI support – Our CoreMIDI binding is OO, baked into system – Equivalent to what 3rd party APIs people use • AudioUnit – Now complete supported (since 6.2) – Full API coverage • AudioToolbox – Improved support for multiple audio channels – Strongly typed APIs Released
- 43. CFNetwork-powered HttpClient • Use Apple’s CFNetwork for your HttpClient – Avoid StartWWAN (Url call) – Turns on Radio for you – Integrates with Async • Replace: var client = new HttpClient () • With: var client = new HttpClient (new CFNetworkHandler ()) Beta
- 44. New Dispose Semantics • Changes in NSObject() Dispose • If native code references object: – Managed object is kept functional – Actual shut down happens when native code releases the reference. • Allows Dispose() of objects that might still be used by the system. Released
- 45. Razor Integration • Sometimes you want to generate HTML • Razor offers a full template system – Blend HTML and C# – Code completion in HTML • Easily pass parameters from C# to Template Released
- 46. New File -> Text Template -> Razor Released
- 47. Razor • Creating template, passing data: – Model property, typed in cshtml file var template = new HtmlReport () { Model = data }; • Run: class HtmlReport { string GenerateString () void Generate (TextWriter writer) } Released
- 48. THANK YOU