仅当从UIButton选择器ARC直接调用时，自定义委托才有效

Question

我正在尝试使用委托方法将一个视图推到另一个视图。 该方法仅在以下代码时有效，并且不会为委托返回null： [button addTarget:self action:@selector(pushView:) forControlEvents:UIControlEventTouchUpInside]; 更改为[button addTarget:delegate action:@selector(pushViewController:) forControlEvents:UIControlEventTouchUpInside];针对[button addTarget:delegate action:@selector(pushViewController:) forControlEvents:UIControlEventTouchUpInside]; 。 否则，委托返回null。 我认为这是ARC无法在ViewController中保留ContentViewController的问题。 请帮忙！

注意：我正在使用ARC

ContentViewController

@class ContentViewController;
@protocol ContentViewControllerDelegate <NSObject>
@required
-(void)pushViewController:(UIViewController *)viewController;
@end

@interface ContentViewController : UIViewController 
{
    __weak id <ContentViewControllerDelegate> delegate;    
}

@property (weak) __weak id <ContentViewControllerDelegate> delegate;

- (void)pushView:(UIViewController *)viewController;

@end


**ContentViewController.m**

#import "ContentViewController.h"

@implementation ContentViewController

@synthesize delegate;

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

    UIButton* button = [UIButton buttonWithType:UIButtonTypeCustom];

    button.frame = CGRectMake(0, 300, 250, 30);

    button.backgroundColor = [UIColor grayColor];

    [button setTitle:@"Test Button" forState:UIControlStateNormal];

    [button addTarget:self action:@selector(pushView:) forControlEvents:UIControlEventTouchUpInside]; 

    [self.view addSubview:button];

}

- (void)pushView:(UIViewController *)viewController
{             
    if([delegate respondsToSelector:@selector(pushViewController:)]) 
        [delegate pushViewController:viewController];

    NSLog(@"pushView");

}

ViewController

#import "ContentViewController.h"

@interface ViewController : UIViewController <ContentViewControllerDelegate>
{
    IBOutlet UINavigationController *navigationController;
    __weak IBOutlet UIButton *navigationButton;
}

@property (strong, nonatomic) IBOutlet UINavigationController *navigationController;
@property (strong, nonatomic) ContentViewController *contentViewController;

@end

#import "ViewController.h"
#import "BinViewController.h"
#import <QuartzCore/QuartzCore.h>

@implementation ViewController
@synthesize navigationController;
@synthesize contentViewController;

#pragma mark - View lifecycle

- (void)viewDidLoad
{
    [super viewDidLoad];

    // Add the navigationController and set the frame
    self.navigationController.view.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);

    [self.view addSubview:navigationController.view];

    // Init ContentViewController to set the delegate
    contentViewController = [[ContentViewController alloc] init];
    // Set the delegate
    contentViewController.delegate = self;

}

#pragma mark - ContentViewControllerDelegate Methods

-(void)pushViewController:(UIViewController *)viewController 
{    
    // This is here just to see if this instance method work ... I haven't actually sent it a view to push 
    BinViewController *binViewController = [[BinViewController alloc] init];
    [self.navigationController pushViewController:binViewController animated:YES];
}

编辑：此图像应有助于解释视图层次结构以及我在这里所做的事情。

Answer 1

最终使用NSNotificationcenter而不是自定义委托。 谢谢您的帮助。

编辑：更改了我的应用程序以使用新的iOS5 UIViewController包含。 好多了！