iOS：滑动UIView on / off屏幕

我的安装
我在Xcode 4中使用单视图应用程序模板.
2.对于xib的“main / border”视图,我添加了2个UIViews(LeftPanel和RightPanel)和一个UIButton(ShowHideButton).
我已经将LeftPanel的绿色和RightPanel蓝色化,以便更容易看清.
4.加载视图时,两个面板均可见,UIButton具有“隐藏面板”文本.
5.按下按钮后,LeftPanel应该滑出屏幕(向左),RightPanel应该展开以占用它的原始空间加上LeftPanel腾出的空间.
此时,ShowHideButton应将其文本更改为“显示面板”.
7.再次按下按钮时,LeftPanel应该滑回到屏幕上(从左边),RightPanel应该缩小到“放回”原来的空间.
此时,ShowHideButton应将其文本更改为“隐藏面板”.

我正在使用animateWithDuration实现动画：动画：完成：.到目前为止,关闭屏幕的转换工作正常(实际上很好).
令我困扰的是当我尝试把LeftPanel带回来的时候,我得到一个EXC_BAD_ACCESS.我已经发布了我的代码,我已经看了它,但我真的看不到我正在访问的那个被释放(或者导致EXC_BAD_ACCESS的任何事情).

DrawerTestingViewController.h
#import <UIKit/UIKit.h>

typedef enum {
    kHidden,kShown
} PanelState;

@interface DrawerTestingViewController : UIViewController {

    PanelState   currentState;

    UIButton    *showHideButton;

    UIView      *leftPanel;
    UIView      *rightPanel;
}

@property (assign,nonatomic)          PanelState   CurrentState;

@property (strong,nonatomic) IBOutlet UIButton     *ShowHideButton;

@property (strong,nonatomic) IBOutlet UIView       *LeftPanel;
@property (strong,nonatomic) IBOutlet UIView       *RightPanel;

- (IBAction)showHidepressed:(id)sender;

@end

DrawerTestingViewController.m
#import "DrawerTestingViewController.h"

@implementation DrawerTestingViewController

@synthesize CurrentState    = currentState;
@synthesize LeftPanel       = leftPanel;
@synthesize RightPanel      = rightPanel;
@synthesize ShowHideButton  = showHideButton;

#pragma mark - My Methods

- (IBAction)showHidepressed:(id)sender
{
    switch ([self CurrentState]) {
        case kShown:
            // Hide the panel and change the button's text
            // 1. Hide the panel
            [UIView animateWithDuration:0.5 
                animations:^{
                // b. Move left panel from (0,w,h) to (-w,h)
                CGRect currLeftPanelRect = [[self LeftPanel] frame];
                currLeftPanelRect.origin.x = -1 * currLeftPanelRect.size.width;
                [[self LeftPanel] setFrame:currLeftPanelRect];
                // c. Expand right panel from (x,h) to (0,w + x,h)
                CGRect currRightPanelRect = [[self RightPanel] frame];
                currRightPanelRect.origin.x = 0;
                currRightPanelRect.size.width += currLeftPanelRect.size.width;
                [[self RightPanel] setFrame:currRightPanelRect];}
                completion:NULL];
            // 2. Change the button's text
            [[self ShowHideButton] setTitle:@"Show Panel" forState:UIControlStatenormal];
            // 3. Flip [self CurrentState]
            [self setCurrentState:kHidden];
            break;
        case kHidden:
            // Show the panel and change the button's text
            // 1. Show the panel
            [UIView animateWithDuration:0.5 
                animations:^{
                // b. Move left panel from (-w,h)
                CGRect currLeftPanelRect = [[self LeftPanel] frame];
                currLeftPanelRect.origin.x = 0;
                [[self LeftPanel] setFrame:currLeftPanelRect];
                // c. Expand right panel from (0,h) to (leftWidth,w - leftWidth,h)
                CGRect currRightPanelRect = [[self RightPanel] frame];
                currRightPanelRect.origin.x = currLeftPanelRect.size.width;
                currRightPanelRect.size.width -= currLeftPanelRect.size.width;
                [[self RightPanel] setFrame:currRightPanelRect];}
                completion:NULL];
            // 2. Change the button's text
            [[self ShowHideButton] setTitle:@"Hide Panel" forState:UIControlStatenormal];
            // 3. Flip [self CurrentState]
            [self setCurrentState:kShown];
            break;
        default:
            break;
    }
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self setCurrentState:kShown];
}

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    switch ([self CurrentState]) {
        case kShown:
            [[self ShowHideButton] setTitle:@"Hide Panel" forState:UIControlStatenormal];
            break;
        case kHidden:
            [[self ShowHideButton] setTitle:@"Show Panel" forState:UIControlStatenormal];
            break;
        default:
            break;
    }
}

@end

我错过了一些超基本的东西吗？有人可以帮忙吗？

谢谢！

编辑：
我再试过两件事：
问题似乎与将屏幕外观看在屏幕上有关,因为LeftPanel离屏开始让我有同样的问题.
2.通过代码可靠地导致Xcode(4 Beta for Lion)崩溃.以下是详细信息(每次崩溃都是这样)：

/SourceCache/DVTFoundation/DVTFoundation-867/Framework/Classes/FilePaths/DVTFilePath.m:373中的ASSERTION FAILURE
详细信息：空字符串不是有效的路径
目的：
方法：_filePathForParent：fileSystemRepresentation：length：allowCreation：
线程：{name =(null),num = 55}
提示：无
回溯：
0 0x00000001068719a6 – [IDEAssertionHandler handleFailureInMethod：object：fileName：lineNumber：messageformat：arguments：](在IDEKit中)
1 0x0000000105f3e324 _DVTAssertionFailureHandler(在DVTFoundation中)
2 0x0000000105edd16f [DVTFilePath _filePathForParent：fileSystemRepresentation：length：allowCreation：](在DVTFoundation中)
3 0x0000000105edcd4d [DVTFilePath _filePathForParent：pathString：](在DVTFoundation中)
4 0x0000000105ede141 [DVTFilePath filePathForPathString：](在DVTFoundation中)
5 0x00000001064a8dde – [IDEIndex queryProviderForFile：highPriority：](在IDEFoundation中)
6 0x000000010655193b – [IDEIndex(IDEIndexQueries)symbolsMatchingName：inContext：withCurrentFileContentDictionary：](在IDEFoundation中)
7 0x000000010aca6166 __68- [IDESourceCodeEditor symbolsForExpression：inQueue：completionBlock：] _ block_invoke_01561(在IDESourceEditor中)
8 0x00007fff93fb490a _dispatch_call_block_and_release(在libdispatch.dylib中)
9 0x00007fff93fb615a _dispatch_queue_drain(在libdispatch.dylib中)
10 0x00007fff93fb5fb6 _dispatch_queue_invoke(在libdispatch.dylib中)
11 0x00007fff93fb57b0 _dispatch_worker_thread2(在libdispatch.dylib中)
12 0x00007fff8bb5e3da _pthread_wqthread(在libsystem_c.dylib中)
13 0x00007fff8bb5fb85 start_wqthread(在libsystem_c.dylib中)

更新：屏幕截图
显示面板(启动状态)

面板隐藏(按钮按下后成功转换)

错误：再次按下按钮会导致故障