改造 UITabBarController

之前看到网上有不少同学自己实现了一些别具一格的系统控件，有一些做得很漂亮。今天我看到了一个UITabBarController的自定义实现，于是我也自己实现了一个TabBarController; 与其他自定义的实现不同，我这个实现自己不新增任何类，也不添加任何资源文件（如图片），完全靠改造系统的UITabBarController实现，在这里我自定义了一个继承UITabBarController的类RZTabBarController(其实也可以不定义它，但是处于个人的私心，我还是用我的名字前缀命名他吧……^_^……)。好，闲话少叙，贴出我的实现代码：

//
// RZTabBarController.h
// CustomTabBarController
//
#import <UIKit/UIKit.h>

@interface RZTabBarController : UITabBarController <UITabBarControllerDelegate> {
@private
NSUInteger lastSelectedIndex;
}

@end

在这个实现文件中我为了不让它感觉太空旷就加了一个私有变量 lastSelectedIndex 我们将在实现文件中用到它，动然如果我们不自定义一个新的类，我们完全可以将它作为一个全局静态变量声明在实现文件中。

//
// RZTabBarController.m
// CustomTabBarController
//

#import "RZTabBarController.h"
#import <QuartzCore/QuartzCore.h>

@implementation RZTabBarController
// The designated initializer. Override if you create the controller programmatically and want to perform customization that is not appropriate for viewDidLoad.
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization.
       self.delegate = self;
    }
    return self;
}

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
    [super viewDidLoad];
   self.delegate = self;
}

- (void)didReceiveMemoryWarning {
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];
    // Release any cached data, images, etc. that aren't in use.
}

- (void)viewDidUnload {
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

- (void)dealloc {
    [super dealloc];
}

#pragma mark -
#pragma mark UITabBarControllerDelegate
- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController {
   NSInteger index = tabBarController.selectedIndex;
   if (index > 4) {
       index = 4;
   }
   UIControl *selectedItem = [[tabBarController.tabBar subviews] objectAtIndex:index];
   UIView *indicatorView = [selectedItem valueForKey:@"_selectedIndicator"];
   NSInteger distanceIndex = lastSelectedIndex - index;
   CGRect originFrame = indicatorView.frame;
   CGRect customFrame = indicatorView.frame;
   customFrame.origin.x = distanceIndex * customFrame.size.width;
   indicatorView.frame = customFrame;
   [UIView beginAnimations:nil context:UIGraphicsGetCurrentContext()];
   [UIView setAnimationDuration:0.25];
   indicatorView.frame = originFrame;
   [UIView commitAnimations];

   CATransition *animation = [CATransition animation];
   animation.timingFunction = UIViewAnimationCurveEaseInOut;
   animation.subtype = kCATransitionFromBottom;
   animation.duration = 0.25;

   UIImageView *imageView = nil;
   NSArray *subviews = [selectedItem subviews];
   if ([subviews count] > 2) {
       imageView = [subviews objectAtIndex:1];
   } else {
       imageView = [subviews objectAtIndex:0];
   }
   animation.type = @"rippleEffect";
   [imageView.layer addAnimation:animation forKey:@"anmation"];

   UILabel *label = [selectedItem valueForKey:@"_label"];
   animation.type = @"cube";
   [label.layer addAnimation:animation forKey:@"anmation"];

   lastSelectedIndex = index;
}

- (void)tabBarController:(UITabBarController *)tabBarController didEndCustomizingViewControllers:(NSArray *)viewControllers changed:(BOOL)changed {
   NSArray *array = tabBarController.tabBar.subviews;
   array = [array sortedArrayUsingComparator:^(id control1, id control2) {
       NSComparisonResult result = NSOrderedSame;
       if (((UIControl *)control1).frame.origin.x > ((UIControl *)control2).frame.origin.x) {
           result = NSOrderedDescending;
       } else if (((UIControl *)control1).frame.origin.x == ((UIControl *)control2).frame.origin.x) {
           result = NSOrderedSame;
       } else if (((UIControl *)control1).frame.origin.x < ((UIControl *)control2).frame.origin.x) {
           result = NSOrderedAscending;
       }
       return result;
   }];
   [tabBarController.tabBar setValue:array forKey:@"_subviewCache"];
}

@end

其实在实现文件中我也只是对UITabBarController的点代理方法进行了个实现，代码如是很多相信大家看到后就自然明白了，可能唯一比较高级的一点就是用到了KeyValueCoding编程，但是使用这个东西的使用我已经在前面的随笔中也已经讲道了，这里是相同的作用。

因为这个一个动态的过程，我就没有办法给大家贴出图来了，想要试试的同学可以将我的代码粘贴一下。