CYLTabBarController

CYLTabBarController offers several advantages for iOS developers:

• Lottie Animation Support: Implement animated TabBar styles using Lottie with minimal code.
• Loose Coupling: The library is independent of business logic. It only requires two arrays (controllers and properties) to set up the framework.
• Native System Components: Uses native UITabBar and UITabBarItem objects rather than custom UIButton or UIView subclasses. This ensures consistent push/pop transition animations and allows the use of standard system APIs like [UITabBar appearance] and [UITabBarItem appearance].
• Automatic PlusButton Detection: Automatically detects if a custom CYLPlusButton subclass is provided and adjusts the TabBar item layout accordingly (e.g., supporting both standard WeChat-style and irregular Weibo-style layouts).
• Robust Interaction: Even if a custom PlusButton extends beyond the standard TabBar area, the extended area remains responsive to touch events.
• Advanced Layout Support: Supports custom TabBar heights, icon-only TabBarItems with vertical centering, custom badge views, and nested TabBars with specific PlusButton positioning.

You can create a custom, irregularly shaped plus button by subclassing CYLPlusButton and implementing the CYLPlusButtonSubclassing protocol.

Steps to Implement:

1. Subclass CYLPlusButton and implement the CYLPlusButtonSubclassing protocol.
2. Register the subclass: Call [YourClass registerPlusButton] in your RootViewController's viewDidLoad or in application:didFinishLaunchingWithOptions:. Do not use +load as it may cause crashes on iOS 10.
3. Implement Optional Protocol Methods:
   • + (NSUInteger)indexOfPlusButtonInTabBar: Defines the position of the plus button. If the number of tab items is odd, this method must be implemented to avoid an exception.
   • + (CGFloat)multiplierOfTabBarHeight:(CGFloat)tabBarHeight: Adjusts the Y-axis center of the button. A value of 0.5 is centered. Values < 0.5 move it up, > 0.5 move it down.
   • + (CGFloat)constantOfPlusButtonCenterYOffsetForTabBarHeight:(CGFloat)tabBarHeight: Provides a fixed offset. If implemented without multiplierOfTabBarHeight, it applies an offset to the default position.
   • + (UIViewController *)plusChildViewController: Returns the view controller to present when the plus button is tapped.
   • + (BOOL)shouldSelectPlusChildViewController: Determines if the plus button should trigger a selection.

Customizing Width

The width of other TabBarItems is automatically calculated as: TabBarItem Width = (Total TabBar Width - PlusButton Width) / (Number of TabBarItems) To change the width of the items, simply change the frame/size of your PlusButton.

Removing Tab Bar Shadow

If your custom button extends beyond the tab bar boundary, you may need to hide the default shadow:

// For iOS 10+
[self hideTabBarShadowImageView];

// Alternative approach
[[UITabBar appearance] setShadowImage:[[UIImage alloc] init]];

To set up the tab bar, you need to provide two arrays: one for the viewControllers and one for the tabBarItemsAttributes.

Tab Bar Item Attributes

Each item in the attributes array is a dictionary containing:

• CYLTabBarItemTitle: The title of the item. If omitted, only the icon is displayed and it will be centered.
• CYLTabBarItemImage: The icon for the normal state. Supports NSString (image name) or UIImage.
• CYLTabBarItemSelectedImage: The icon for the selected state. Supports NSString or UIImage.

Implementation Example

Subclass CYLTabBarController and override the necessary methods to provide your controllers and attributes.

// Example implementation in Objective-C

@interface MainTabBarController : CYLTabBarController
@end

@implementation MainTabBarController

- (instancetype)init {
    if (!(self = [super init])) {
        return nil;
    }
    
    UIEdgeInsets imageInsets = UIEdgeInsetsZero;
    UIOffset titlePositionAdjustment = UIOffsetMake(0, -3.5);
    
    CYLTabBarController *tabBarController = [CYLTabBarController tabBarControllerWithViewControllers:self.viewControllers
                                                                               tabBarItemsAttributes:self.tabBarItemsAttributesForController
                                                                                         imageInsets:imageInsets
                                                                             titlePositionAdjustment:titlePositionAdjustment
                                                                                             context:nil
                                             ];
    [self customizeTabBarAppearance:tabBarController];
    return (self = (MainTabBarController *)tabBarController;
}

- (NSArray *)viewControllers {
    CYLHomeViewController *firstViewController = [[CYLHomeViewController alloc] init];
    UIViewController *firstNavigationController = [[CYLBaseNavigationController alloc] initWithRootViewController:firstViewController];
    
    CYLSameCityViewController *secondViewController = [[CYLSameCityViewController alloc] init];
    UIViewController *secondNavigationController = [[CYLBaseNavigationController alloc] initWithRootViewController:secondViewController];
    
    return @[firstNavigationController, secondNavigationController];
}

- (NSArray *)tabBarItemsAttributesForController {
    NSDictionary *firstTabBarItemsAttributes = @{
        CYLTabBarItemTitle : @"首页",
        CYLTabBarItemImage : @