Question

大家好日子，

使用Storyboad时，我无法在ViewController中调用方法刷新。但是，如果我创建没有Storyboard的项目，只有NIB，它就可以工作。为什么它不起作用以及如何克服这个问题？

这是我的代码：

AppDelegate.h

#import <UIKit/UIKit.h>

@class ViewController;


@interface AppDelegate : NSObject <UIApplicationDelegate>
{
    UIWindow *window;
    ViewController *viewController;
}

@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain) IBOutlet ViewController *viewController;

@end

AppDelegate.m

#import "AppDelegate.h"
#import "ViewController.h"

@implementation AppDelegate

@synthesize window;
@synthesize viewController;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    // Override point for customization after application launch.
    return YES;
}

- (void)applicationWillResignActive:(UIApplication *)application
{
    // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
    // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}

- (void)applicationDidEnterBackground:(UIApplication *)application
{
    // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later. 
    // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}

- (void)applicationWillEnterForeground:(UIApplication *)application
{
    // Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
    NSLog(@"app will enter foreground");
    [viewController refresh:NULL]; 
}

- (void)applicationDidBecomeActive:(UIApplication *)application
{
    // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}

- (void)applicationWillTerminate:(UIApplication *)application
{
    // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
}

@end

ViewController.h

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController

-(IBAction) refresh:(id)sender;

@end

ViewController.m

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}

- (void)loadData {
    // contains information the ViewController makes use of
}

-(IBAction)refresh:(id) sender {
    [self loadData];
}

@end

Answer 1

使用情节提要时，不会填充应用程序委托中的viewController属性。在日志语句中包含该值以进行确认 - 它将为null。

注册视频控制器以获取通知，然后让它自己处理刷新。

在viewDidLoad中：

[super viewDidLoad];
[[NSNotificationCenter defaultCenter] addObserver:self 
    selector:@selector(refresh:) 
    name:UIApplicationDidBecomeActiveNotification
    object: nil];

你也想在dealloc / viewDidUnload中删除这个观察者。

使用Storyboard时，从appdelegate调用视图控制器方法不起作用

1 个答案: