ADVANCED_CUSTOMISATION.md

Advanced Customisation

Tabman can be customised to your own liking; including the definition of custom bars and indicators.

Contents

• Creating a custom TabmanBar
• Using an external TabmanBar
• Embedding TabmanBar in an external view

Creating a custom TabmanBar

1. Simply create a bar object that inherits from TabmanBar.

import UIKit
import Tabman
import Pageboy

class MyCustomBar: TabmanBar {
}

2. Implement and override the following methods:

override func defaultIndicatorStyle() -> TabmanIndicator.Style {
	// declare default indicator style here
	return .line
}

override func usePreferredIndicatorStyle() -> Bool {
	// whether the bar should use preferredIndicatorStyle
	return true
}

override func construct(in contentView: UIView,
                        for items: [TabmanBarItem]) {
	// create your bar here     
}

override func add(indicator: TabmanIndicator, to contentView: UIView) {
	// add the indicator to the bar here
}

override func update(forPosition position: CGFloat,
                direction: PageboyViewController.NavigationDirection,
                indexRange: Range<Int>,
                bounds: CGRect) {
	super.update(forPosition: position, direction: direction,
				 indexRange: Range<Int>,
				 bounds: CGRect)
				 
	// update your bar contents for a positional update here              
}

override func update(forAppearance appearance: Appearance, 
                     defaultAppearance: Appearance) {
	super.update(forAppearance: appearance,
	             defaultAppearance: defaultAppearance)
        
	// update the bar appearance here
}

The above functions provide all the necessary lifecycle events for keeping a TabmanBar correctly configured and up to date with the page view controller it responds to.

Tabman uses intrinsicContentSize to calculate the required height of the bar, simply override this to manually specify an explicit height.

3. Configure the TabmanViewController to use the new custom style.

override func viewDidLoad() {
	super.viewDidLoad()
	
	self.bar.style = .custom(type: MyCustomBar.self)
}

Using a custom TabmanIndicator

As seen above, when creating a TabmanBar subclass you can specify the style for the indicator in indicatorStyle().

override func indicatorStyle() -> TabmanIndicator.Style {
	return .line
}

This can be used to return a custom view to use as the TabmanIndicator:

1. Create an object that inherits from TabmanIndicator.

import UIKit
import Tabman
import Pageboy

class MyCustomIndicator: TabmanIndicator {
}

2. Implement and override the following methods:

public override func constructIndicator() {
        super.constructIndicator()
        
        // create your indicator here
}

3. Configure your custom TabmanBar to use your custom indicator.

override func indicatorStyle() -> TabmanIndicator.Style {
	return .custom(type: MyCustomIndicator.self)
}

Using an external TabmanBar

TabmanViewController supports the ability to use an external TabmanBar rather than the internally managed one if required.

This is available by calling the attach(bar:) function as follows:

class MyTabmanViewController: TabmanViewController {

	func viewDidLoad() {
		super.viewDidLoad()
		
		let customBar = CustomTabmanBar()
		self.attach(bar: customBar)
	}
}

This will hide the internally managed TabmanBar and provide updates to the attached bar.

If required, this bar can also be detached later by calling:

// detaches and returns the currently attached TabmanBar
func detachAttachedBar() -> TabmanBar?

Embedding TabmanBar in an external view

You can also embed the internally managed TabmanBar in an external view. This allows for all the advantages of internal management (Style switching etc.) but in a specified view elsewhere in the view hierarchy.

This is available with the embedBar(inView:) function.

class MyTabmanViewController: TabmanViewController {

	let customBarView = UIView()

	func viewDidLoad() {
		super.viewDidLoad()
		
		self.embedBar(inView: customBarView)
	}
}

When called, this will add the TabmanBar as a subview within the custom view, and pin it to all four edges (leading, top, trailing, bottom).

You can also disembed the TabmanBar from the external view like this:

func disembedBar()

This will restore normal behaviour and embed the bar in its original internal location.