Question

我想将切换ViewControllers的代码放到一个名为SwitchController的类中。但没有任何反应。

以下是代码：

// AppDelegate.m

-(BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
        self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
        // Override point for customization after application launch.
        self.window.backgroundColor = [UIColor whiteColor];

        RootViewController *root = [[RootViewController alloc] init];
        [self.window setRootViewController:root];

        [self.window makeKeyAndVisible];
        return YES;
}

// SwitchController.h

@interface SwitchController : NSObject

@property (strong,nonatomic) RootViewController *rootViewController;

+(SwitchController *)sharedInstance;
-(void)requestToSwitchViewController:(NSInteger)tag;

@end

// SwitchController.m

#import "SwitchController.h"
#import "FirstViewController.h"
#import "SecondViewController.h"

@implementation SwitchController

@synthesize rootViewController = _rootViewController;

-(id)init
{
    self = [super init];
    if (self == nil)
    {
        _rootViewController = [[RootViewController alloc] init];
    }
    return self;
}

+(SwitchController *)sharedInstance
{
    static SwitchController *sharedSingleton = nil;
@synchronized([SwitchController class])
{
    if(sharedSingleton == nil)
    {
        sharedSingleton = [[self alloc] init];
    }
}
return sharedSingleton;
}

-(void)requestToSwitchViewController:(NSInteger)tag
{
    switch (tag)
    {
        case 1:
        {
            FirstViewController *first = [[FirstViewController alloc] init];
            [self.rootViewController presentViewController:first animated:YES completion:nil];
        }
            break;
         .........  //Do something else
        default:
            break;
    }
}

@end

//这是self.window.rootViewController ------ RootViewController.m

//在这个ViewController的视图中，有一个按钮，在按下时，它将执行以下操作

    - (IBAction)pressed:(id)sender
    {
        [[SwitchController sharedInstance] requestToSwitchViewController:[(UIButton *)sender tag]];
    }

那么，我的代码有什么问题吗？

按下按钮时为什么没有发生？

Answer 1

可能有几个问题..

1）检查您的按钮插座是否正确连接到此方法-(IBAction)pressed:(id)sender;

2）在@synthesize

中的SwitchController.m之后添加此行

static SwitchController *sharedSingleton = nil;

3）改变你的方法

+(SwitchController *)sharedInstance
{
    if(sharedSingleton == nil)
    {
        sharedSingleton = [[self allocWithZone:NULL] init];
    }
  return sharedSingleton;
}

4）从-id(init)方法

中删除此行

// You do not need to re-initialize the root view controller
_rootViewController = [[RootViewController alloc] init];

5）检查按钮是否有效。在调用此方法之前requestToSwitchViewController:检查它记录的内容

<强>更新

尝试这样:(为此，您需要create a property for navigation controller appDelegate并合成它。

switch (tag)
{
    case 1:
    {
        FirstViewController *first = [[FirstViewController alloc] init];
        appDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
        [appDelegate.navigationController presentViewController:first animated:YES completion:nil];
    }
    .....
  .........
 }

Answer 2

我猜你只是定义了viewController，你也需要定义View。他们是不同的东西。

切换ViewControllers，但没有任何反应？

2 个答案: