iOS : How to detect Shake motion?

Question

I added the following code to my appDelegate.m

- (void)motionBegan:(UIEventSubtype)motion withEvent:(UIEvent *)event
{
}

- (void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event
{
    if (motion == UIEventSubtypeMotionShake )
    {
        // User was shaking the device. Post a notification named "shake".
        [[NSNotificationCenter defaultCenter] postNotificationName:@"shake" object:self];
    }
}

- (void)motionCancelled:(UIEventSubtype)motion withEvent:(UIEvent *)event
{   
}

- (void)shakeSuccess
{
    // do something...
}

and then I added :

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    // Override point for customization after application launch.
    // INIT THE BACKGROUND PATH STRING

    [self refreshFields];
    [self.window addSubview:navController.view];
    [self.window makeKeyAndVisible];
    ***[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(shakeSuccess) name:@"shake" object:nil];***

    return YES;
}

When I start my app on my iPhone, the method named "shakeSuccess" doesn't called. What should I do to implement this function in my app? any idea?

Answer 1

This might help you...
https://stackoverflow.com/a/2405692/796103

He says that you should set the UIApplication's applicationSupportsShakeToEdit to YES. and override 3 methods in your VC:

-(BOOL)canBecomeFirstResponder {
    return YES;
}

-(void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    [self becomeFirstResponder];
}

- (void)viewWillDisappear:(BOOL)animated {
    [self resignFirstResponder];
    [super viewWillDisappear:animated];
}

The rest of your code is fine. (the -motionEnded:withEvent:)

Answer 2

You could do something like this...

Firstly...

Set the applicationSupportsShakeToEdit property in the App's Delegate:

- (void)applicationDidFinishLaunching:(UIApplication *)application {

    application.applicationSupportsShakeToEdit = YES;

    [window addSubview:viewController.view];
    [window makeKeyAndVisible];
}

Secondly...

Add/Override canBecomeFirstResponder, viewDidAppear: and viewWillDisappear: methods in your View Controller:

-(BOOL)canBecomeFirstResponder {
    return YES;
}

-(void)viewDidAppear:(BOOL)animated {
   [super viewDidAppear:animated];
   [self becomeFirstResponder];
}

- (void)viewWillDisappear:(BOOL)animated {
    [self resignFirstResponder];
    [super viewWillDisappear:animated];
 }

Thirdly...

Add the motionEnded method to your View Controller:

- (void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event
{
   if (motion == UIEventSubtypeMotionShake)
   {
    // your code
   }
 }

That should work if the first answer did not and this is only quickly typed not tested:)

Answer 3

If you want to be able to detect the shake motion across the app, the best way is to override the class of your application with a custom class.

And then implement this in your custom application class

@implementation PSApplication

- (void)sendEvent:(UIEvent *)event
{
    if ( event.type == UIEventTypeMotion && event.subtype == UIEventSubtypeMotionShake ) {
        [[NSNotificationCenter defaultCenter] postNotificationName:@"shakeNotification" object:nil];
    }

    [super sendEvent:event];
}

@end

Answer 4

I extended UIApplication class and added class reference to main: MyApplication.h

@interface MyApplication : UIApplication

@end

MyApplication.m

@implementation MyApplication

- (void) sendEvent:(UIEvent *)event
{
    if( event && (event.subtype==UIEventSubtypeMotionShake))
    {
        AppDelegate *objAppDelegate = (AppDelegate *)[UIApplication sharedApplication].delegate;

        [objAppDelegate doWhatEver];
        [super sendEvent:event];
    }
    else
    {
        [super sendEvent:event];
    }
}

@end

And the last step in main.m

int main(int argc, char *argv[])
{
return UIApplicationMain(argc, argv, NSStringFromClass([MyApplication class]), NSStringFromClass([AppDelegate class]));
}

This works in all cases.