UITabBar items jumping on back navigation on iOS 12.1

Question

I have an iOS app with UITabBarController on a master screen, navigating to a detail screen hiding the UITabBarController with setting hidesB

Answer 1

You can override - (UIEdgeInsets)safeAreaInsets method for few iOS 12 subversions with this:

- (UIEdgeInsets)safeAreaInsets {
    UIEdgeInsets insets = [super safeAreaInsets];
    CGFloat h = CGRectGetHeight(self.frame);
    if (insets.bottom >= h) {
        insets.bottom = [self.window safeAreaInsets].bottom;
    }
    return insets;
}

Answer 2

Here's a solution that can handle rotation and tab bar items being added or removed:

class FixedTabBar: UITabBar {

    var buttonFrames: [CGRect] = []
    var size: CGSize = .zero

    override func layoutSubviews() {
        super.layoutSubviews()

        if UIDevice.current.systemVersion >= "12.1" {
            let buttons = subviews.filter {
                String(describing: type(of: $0)).hasSuffix("Button")
            }
            if buttonFrames.count == buttons.count, size == bounds.size {
                zip(buttons, buttonFrames).forEach { $0.0.frame = $0.1 }
            } else {
                buttonFrames = buttons.map { $0.frame }
                size = bounds.size
            }
        }
    }
}

Answer 3

I guess it's Apple's bug But you can try this as a hot fix: just create a class for your tabBar with following code:

import UIKit

class FixedTabBar: UITabBar {

    var itemFrames = [CGRect]()
    var tabBarItems = [UIView]()


    override func layoutSubviews() {
        super.layoutSubviews()

        if itemFrames.isEmpty, let UITabBarButtonClass = NSClassFromString("UITabBarButton") as? NSObject.Type {
            tabBarItems = subviews.filter({$0.isKind(of: UITabBarButtonClass)})
            tabBarItems.forEach({itemFrames.append($0.frame)})
        }

        if !itemFrames.isEmpty, !tabBarItems.isEmpty, itemFrames.count == items?.count {
            tabBarItems.enumerated().forEach({$0.element.frame = itemFrames[$0.offset]})
        }
    }
}

Answer 4

If you still want to keep your tab bar translucent you need to subclass from UITabBar and override property safeAreaInsets

class MyTabBar: UITabBar {

private var safeInsets = UIEdgeInsets.zero

@available(iOS 11.0, *)
override var safeAreaInsets: UIEdgeInsets {
    set {
        if newValue != UIEdgeInsets.zero {
            safeInsets = newValue
        }
    }
    get {
        return safeInsets
    }
} 

}

The idea is to not allow system to set zero insets, so tab bar won't jump.

Answer 5

here is the swift code

extension UIApplication {
open override var next: UIResponder? {
    // Called before applicationDidFinishLaunching
    SwizzlingHelper.enableInjection()
    return super.next
}

}

class SwizzlingHelper {

static func enableInjection() {
    DispatchQueue.once(token: "com.SwizzlingInjection") {
        //what to need inject
        UITabbarButtonInjection.inject()
    }

} more information https://github.com/tonySwiftDev/UITabbar-fixIOS12.1Bug

Answer 6

Apple has now fixed that in iOS 12.1.1