Adding iOS-specific Formatting

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last updated: 2016-01

One way to set iOS-specific formatting is to create a custom renderer for a control and set platform-specific styles and colors for each platform.

Other options to control the way your Xamarin.Forms iOS app's appearance include:

These alternatives are discussed below.

Customizing Info.plist

The Info.plist file lets you configure some aspects of an iOS application's renderering, such as how (and whether) the status bar is shown.

For example, the Todo sample uses the following code to set the navigation bar color and text color on all platforms:

var nav = new NavigationPage (new TodoListPage ());
nav.BarBackgroundColor = Color.FromHex("91CA47");
nav.BarTextColor = Color.White;

The result is shown in the screen snippet below. Notice that the status bar items are black (this cannot be set within Xamarin.Forms because it is a platform-specific feature).

Ideally the status bar would also be white - something we can accomplish directly in the iOS project. Add the following entries to the Info.plist to force the status bar to be white:

or edit the corresponding Info.plist file directly to include:

<key>UIStatusBarStyle</key>
<string>UIStatusBarStyleLightContent</string>
<key>UIViewControllerBasedStatusBarAppearance</key>
<false/>

Now when the app is run, the navigation bar is green and its text is white (due to Xamarin.Forms formatting) and the status bar text is also white thanks to iOS-specific configuration:

UIAppearance API

The UIAppearance API can be used to set visual properties on many iOS controls without having to create a custom renderer.

Adding a single line of code to the AppDelegate.cs FinishedLaunching method can style all controls of a given type using their Appearance property. The following code contains two examples - globally styling the tab bar and switch control:

AppDelegate.cs in the iOS Project

public override bool FinishedLaunching (UIApplication app, NSDictionary options)
{
  // tab bar
    UITabBar.Appearance.SelectedImageTintColor = UIColor.FromRGB(0x91, 0xCA, 0x47); // green
  // switch
    UISwitch.Appearance.OnTintColor = UIColor.FromRGB(0x91, 0xCA, 0x47); // green
    // required Xamarin.Forms code
    Forms.Init ();
    LoadApplication (new App ());
    return base.FinishedLaunching (app, options);
}

UITabBar

By default, the selected tab bar icon in a TabbedPage would be blue:

To change this behavior, set the UITabBar.Appearance property:

UITabBar.Appearance.SelectedImageTintColor = UIColor.FromRGB(0x91, 0xCA, 0x47); // green

This causes the selected tab to be green:

Using this API lets you customize the appearance of the Xamarin.Forms TabbedPage on iOS with very little code. Refer to the Customize Tabs recipe for more details on using a custom renderer to set a specific font for the tab.

UISwitch

The Switch control is another example that can be easily styled:

UISwitch.Appearance.OnTintColor = UIColor.FromRGB(0x91, 0xCA, 0x47); // green

These two screen captures show the default UISwitch control on the left and the customized version (setting Appearance) on the right in the Todo sample:

Other controls

Many iOS user interface controls can have their default colors and other attributes set using the UIAppearance API.

Xamarin Workbook

If it's not already installed, install the Xamarin Workbooks app first. The workbook file should download automatically, but if it doesn't, just click to start the workbook download manually.