tl;dr: F# has a long learning curve (it takes a long time to master) but productivity happens quickly.

I recently wrote my first real application in F#. Although I've been using F# for many of my scripting needs for about a year and use F# to explore iOS APIs …

Xamarin loves F#!

Of course you can use F# to program iOS and Android applications using Xamarin and Visual Studio!

[code lang="fsharp"]
namespace Simple

open System
open MonoTouch.UIKit
open MonoTouch.Foundation
open System.Drawing

type ContentView ( color : UIColor ) as self =
inherit UIView ()
do
self.BackgroundColor \< - color

type SimpleController …

Helpful: http://ivomynttinen.com/blog/the-ios-7-design-cheat-sheet/

There have been great barcode-reading libraries available for Xamarin for some time, but iOS 7 has built-in barcode-recognition support.

There's only one tricky bit: you have to tell the AVCaptureMetadataOutput what types of barcodes you're interested in after you've added it to the AVCaptureSession. (I suppose what happens behind the …

http://www.apple.com/ios/feature-availability/#maps-3d-buildings-in-navigation

The new M7 coprocessor in the iPhone 5S makes pedometer apps trivial:

[code lang="csharp"]
if(CMStepCounter.IsStepCountingAvailable)
{
var counter = new CMStepCounter();
//Last 8 hours
counter.QueryStepCount(NSDate.FromTimeIntervalSinceNow(-8 * 60 * 60), NSDate.Now, NSOperationQueue.CurrentQueue, StepQueryHandler);
}

void StepQueryHandler(int nssteps, NSError error)
{
Console.WriteLine(nssteps);
}
[/code]

I totally forgot a frustrating detail about showing 3D buildings in iOS 7 : it doesn't work in the simulator! You have to use a hardware device!

Multipeer Connectivity allows you to discover and share data with other iOS devices within Bluetooth radio range or on the same WiFi subnet. It is much easier to use than Bonjour.

I wrote a simple MPC chat program in Xamarin.iOS.

There's necessarily a few hundred lines of code, but …

One of the nice features in iOS 7 for old fogeys such as myself is that the user can use the general Settings to increase and decrease the fonts used in apps. This is called "Dynamic Type." Judging by developer forums, I'm not the only one who thought that this …

Did I mention how easy it is to track an iBeacon using Xamarin?

[code lang="csharp"]
locationManager = new CLLocationManager();
var beaconId = new NSUuid("E437C1AF-36CE-4BBC-BBE2-6CE802977C46");
var beaconRegion = new CLBeaconRegion(beaconId, "My Beacon");
locationManager.RegionEntered += (s, e) => {
if(e.Region.Identifier == "My Beacon")
{
Console.WriteLine("Found My Beacon");
//Fire up ranging
locationManager …