I’ve been converting a major App and the Migrate tool works very well but I found a couple of cases, which either it didn’t do or I messed up.

The first is when using a nint as an index in a List. It doesn’t work, as the .NET generics know nothing about nints. So just cast it to an int like this below where _itemsList is a List

Text = _itemsList[(int)row];

Converting NSDate to System.DateTime and vice versa

It’s now a compile error to assign a DateTime to a NSDate or vice versa, the implicit conversion no longer works. I think this is to highlight a subtle bug to do with NSDate is always an UTC time and DateTime is default set to DateTimeKind.Unspecified (when read from database) or DateTimeKind.Locale (when set with DateTime.Today) Source is this stackoverflow answer.

Thankfully the Foundation.NSDate class includes two explicit operators that do the job for you.
NSDate in Xamarin Object Browser

So this works.

            NSDate nDate = (NSDate) DateTime.Now;
            DateTime dDate = (DateTime) nDate;

AVAudioRecorder Changes

The settings used to create an AVAudioRecorder have changed from a NSDictionary to AudioSettings, and the AVAudioRecorder.ToUrl method no longer exists.

Instead create avsettings like this and use the factory method Create to create the AVAudioRecorder.

//Set Settings with the Values and Keys to create the NSDictionary
            avsettings = new AudioSettings(NSDictionary.FromObjectsAndKeys(values, keys));

//Set recorder parameters
            recorder = AVAudioRecorder.Create(url, avsettings, out error);

It’s kind of obvious in retrospect about enabling or disabling animation. It’s part of some code where I’ve added a UIImage onto a MkMapView (Apple’s iOS Controls for displaying a map), that centres the map on your current location when you click it. The button is a gun sight type icon and I’ve located in the bottom right edge of the map.

    private UIButton btnCurrentLoc; // defined at the class level

// in ViewDidLoad
    var ImageCurrentLoc = UIImage.FromBundle("images/currentloc.png");

    btnCurrentLoc = new UIButton() { TintColor = UIColor.Black };
    btnCurrentLoc.SetImage(ImageCurrentLoc, UIControlState.Normal);
    btnCurrentLoc.Frame = new RectangleF(View.Frame.Width-50, View.Frame.Height - 100, ImageCurrentLoc.Size.Width, ImageCurrentLoc.Size.Height);

    btnCurrentLoc.TouchUpInside += (s, e) =>
                    map.SetCenterCoordinate(map.UserLocation.Location.Coordinate,true);  // animated
                    //map.CenterCoordinate = map.UserLocation.Location.Coordinate;       // not animated, moves directly            

  View.AddSubview(map);            // has to be this way round! map first then control

Note that you add the map first to the view then the button.

As it’s commented if you click the btnCurrentLoc button, it will animate the map so you can see it scroll to your location. If you comment out that line and uncomment the line below, when you click the button it will move there immediately.

iPhone MkMapView with home button

My Visual Studio started taking a longish- three to four minutes to load up and then the same when I opened a project. This started after the last Xamarin update. I’ve always found that for best results I have to reboot after an update and then unpair and pair. Sometimes my Mac Mini shows up in the Connection dialog as an IP address and sometime as the name. As the ip is DHCP provided, I figured out using the name was best however..

To cut a long story short, Zone Alarm did not like DNS queries for the Virgin DNS ( and port 53 ) which were resolving the Mac Mini and it was those being blocked that slowed VS down. I figure it must have been a timeout plus maybe some kind of fallback as I could still build projects on the Mac.

So if you ever get that kind of slow down, check your firewall!

I’ve not mastered AutoLayout, but if you want to resize a label, there’s a few of things you need to do. The image below shows a slider used to control a font size.


Resizing a label with a slider

Here I’ve omitted the declarations but fontlabel is a UiLabel, Support.FontSize is a float, and fontSlider is a UISlider. This is the code.

            fontlabel = new UILabel()
                Text = @"Font Size",
                Lines = 1,               
                TextColor = Support.uTextColor,
                BackgroundColor = Support.BackColor,
                LineBreakMode = UILineBreakMode.WordWrap,
                Frame = new RectangleF(10, 320, Frame.Width - 20, 30),
                Font = UIFont.FromName("Helvetica", Support.FontSize)
            fontslider = new UISlider(new RectangleF(5, 350, Frame.Width - 5, 30))
                MinValue = 11f,
                MaxValue = 30f,
                Value = Support.FontSize
            fontslider.ValueChanged += HandleFontSliderChanged;

        private void HandleFontSliderChanged(object sender, EventArgs e)
            Support.FontSize = fontslider.Value;
            fontlabel.Font = UIFont.FromName("Helvetica", Support.FontSize);

Allow enough room for the label to fit at its largest size and having changed the font size in the Slider event, call SizeToFit() on the label. Otherwise you’ll find that the text is truncated when the label is made larger.

Near the end of a project and there’s nothing worse than getting a new release of the development software and getting a real big scare. I got 7.0.4 this morning with the new pairing of Visual Studio to the Xamarin.iOS Build Host running on the Mac.

Mac and Windows Pairing Dialogs

That worked well, but the scare came when I went to upload the newly built app on to my device and got a No Provisioning Profiles Found build error. Weird but as I’d renewed my developer account with Apple yesterday, possibly it was related to that but no it showed fine. The profiles on the iPhone showed fine as well in the Xcode organiser.

Dev profiles in Xcode's organiser

I was a bit worried because my Mac is only 10.7.5 and can’t run Xcode 5 or develop for iOS 7. It will be replaced shortly. However it turned out to be a lot simpler than that. In the Xamarin Studio Preferences, the Developer accounts had been zapped. Just adding my Apple account back in sorted it.

Xamarin Studio Developer Accounts

I added Default.png and the other variations for iPhone 5, retina display fils and they appeared in the Resources folder. These are for loading screens and are built in as part of the bundle after you add them.

However in doing some work on rolling my own Splash screen so it can have text added, I decided to remove them.

In Xamarin Studio (on Mac) you can unset them, but compiling gave 2 errors about missing files. Looking in the info.plist on the source tab revealed that two strings were still there so I manually removed those. I did a clean then a Build and still got the errors. I did a clean and a Rebuild and still got the same errors. Finally I closed Xamarin Studio down, then reopened it and it built fine. Just a minor irritation.

Another Xamarin update- I expect there to be quite a few with iOS 7 now hitting alpha on the Xamarin Studio front. However, MonoDoc keeps wanting to have Apple documentation merged with Xamarin.iOS documentation. Even though it’s done it already. It’s deja vu all over again. Last time it was Visual Studio!


I talked earlier this week about these and have done further work. The problem I was solving was this: The App will be installed from the App Store but is only for a subset of users. It would be very bad if anyone else was able to use it.

So When it’s first run, it looks for Config info. As it’s never been run and this config info is set internally, it comes up with a screen asking for a few fields to be filled in, but only saves the data if a master password is entered. This information is saved out (password fields are used) and then the App kills the main View, recreates it ie effectively it restarts and upon finding the correct information it works properly. This was done in the View’s ViewDidLoad.

What I found was that the ViewWillAppear only appears to fire the first time and not the second following the View being disposed (UiViews are disposable) and then recreated in the a method in ViewController.

At times, some of the lockdowns on iOS can be quite frustrating. It can’t for example send email programmatically which presumably is to prevent spamming. The conversion I’m doing (from Windows Phone) has a requirement to log all functionality and occasionally email these logs.  Yes you can do it on Windows Phone!

Fortunately iOS does allow applications to access the web, so with a few lines of PHP script running on a domain I own (and host), I can have the logs sent via a URL POST which includes some magic values added so that the script can’t be easily abused by spammers. In any case the email is sent to one specific address.