iphone - 自定义委托(delegate)仅在从 UIButton 选择器 ARC 保留问题直接调用时才有效

Question

我正在尝试使用委托(delegate)方法将 View 推送到另一个 View 。该方法仅在此代码:[button addTarget:self action:@selector(pushView:) forControlEvents:UIControlEventTouchUpInside]; 时有效，并且不会为委托(delegate)返回 null。改为[button addTarget:delegate action:@selector(pushViewController:) forControlEvents:UIControlEventTouchUpInside]; .否则，委托(delegate)返回 null。我相信这是 ARC 没有在 ViewController 中保留 ContentViewController 的问题。请帮忙!

注意:我正在使用 ARC

内容 View Controller

@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");

}

View Controller

#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:这张图片应该有助于解释 View 层次结构和我在这里做什么。

Answer 1

最终使用 NSNotificationcenter 而不是自定义委托(delegate)。感谢您的帮助。

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