Acceleration in a for..... loop - iphone

I have a for....loop and the UI then is blocked when in the loop.
Is the accelerometer also blocked?
I have following code in viewDidLoad
- (void)viewDidLoad{
[super viewDidLoad];
UIAccelerometer *accel = [UIAccelerometer sharedAccelerometer];
accel.delegate = self;
accel.updateInterval = 1.0f/60.0f;
}
and further down
- (void)accelerometer:(UIAccelerometer *)acel didAccelerate:(UIAcceleration *)acceleration {
acc=acceleration.x;
}
then an IBAction connected to a button which starts a loop
- (IBAction)doSomething {
for (int n = 1; n<=100;n++) {
// do someting in the loop
NSLog(#"x: %g", acc);
}
}
when logging the accelerometer x value it shows only the first value when the button is pressed and does not update when the loop is running. The same first value is repeating continuously.
Is there a way to log the acceleration when in the loop?

It would seem that UIAccelerometer needs the main thread so is getting blocked by the for...loop. Core Motion also has an accelerometer property in the CMMotionManager object that can report acceleration, and does better backgrounding since it's what Nike+ uses. There are two ways to access it - a pull method where you get the data directly, or a call-back. To be honest, I just tried it and couldn't get the call-back to work (mostly because it requires NSOperationQueue and I don't have much experience with that so I'm probably putting it on the wrong queue), but if you're ok with pulling data, which your approach seems to need, then this works:
CMMotionManager *motionManager = [[CMMotionManager alloc] init];
[motionManager startAccelerometerUpdates];
for (int i = 0; i < 10000; i++)
{
NSLog(#"Acceleration: %f", motionManager.accelerometerData.acceleration.x);
}
I just tried it on a device and the values reported in the for...loop update with the current acceleration.
Source: UIBackgroundModes and UIAccelerometer

Related

Saving user acceleration from iPhone devieMotion to a filetext

I'm using deviceMotion for getting useracceleration(x, y, z). My aim is to create a filetext where in each iteration my application writes the 3 components in a row.
I'm using MotionGraphs code sample.
How is it possible - directly, or is necessary to create an array first?
This array; is it NSMutableArray or NSMutableNumber?
I've been looking for this question and I'm lost. :-(
I'm not an Objective-C expert but I remember Pascal code where I opened a file, and then I was writing in each iteration, but I checked: that programming has changed.
At the beginning we don't take into account different filters or discrimination window. For them, I've implemented freescale procedure. I'm just looking to save accelerometer data / to store data from accelerometer using deviceMotion userAcceleration.
float minX = 1.0f;
float minY = 1.0f;
float minZ = 1.0f;
NSMutableArray *container = [[NSMutableArray alloc] init];
-(void)startUpdatesWithSliderValue:(int)sliderValue
{
NSTimeInterval delta = 0.005;
NSTimeInterval updateInterval = deviceMotionMin + delta * sliderValue;
CMMotionManager *mManager = [(APLAppDelegate *)[[UIApplication sharedApplication] delegate] sharedManager];
APLDeviceMotionGraphViewController * __weak weakSelf = self;
[container addObject:[NSNumber numberWithFloat:deviceMotion.userAcceleration.x]];
[container addObject:[NSNumber numberWithFloat:deviceMotion.userAcceleration.y]];
[container addObject:[NSNumber numberWithFloat:deviceMotion.userAcceleration.z]];
}
//Finally we have to dump data to filetext, this is I donĀ“t know correctly.
1 Create NSMutableArray *container = [[NSMutableArray alloc] init]; to be your container.
2 Within the Accelerometer delegate method for did detect motion be sure to set a min for each of the 3 axis. e.g. float min_X = 1.0f; float min_y =1.0f; float min_Z = 1.0f
-(void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration {
}
3 Use Simple Filter Logic as in: (keep in mind the Acceleration is maxed at +- 2.3g so both positive and negative thresholds need consideration.
if ((acceleration.x > min_X || acceleration.x < -min_X) && (Y's..) && (Z's...) ) {
[container addObject:[NSNumber numberWithFloat:acceleration.x]];
[container addObject:[NSNumber numberWithFloat:acceleration.y]];
[container addObject:[NSNumber numberWithFloat:acceleration.z]];
}
4 The Array should be full of NSNumbers in groups of three (x,y,z).
5 The filter is needed, otherwise the accelerometers can pick small vibrations just sitting on the table.
WARNING: The Array will fill up fast, so Set the Sample Rate to an acceptable range based on how long you want to record data.

How to move a object by titling the screen in cocos2d

i have his code for making movemnt of the object through horizontal postion.
#define kAccelerationSpeed 10
#define kAccelerometerFrequency 200
-(void) accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration
{
CGPoint pt = thePlayer.position ;
CGFloat accel = acceleration.x * kAccelerationSpeed;
pt = [[CCDirector sharedDirector] convertToGL:pt];
pt = ccp (pt.x+accel>0 , yLocationOfPlayer+accel<768 );
}
in init statment
-(id) init
{
// always call "super" init
// Apple recommends to re-assign "self" with the "super" return value
if( (self=[super init])) {
[[UIAccelerometer sharedAccelerometer] setUpdateInterval:(1.0 / kAccelerometerFrequency)];
[[UIAccelerometer sharedAccelerometer] setDelegate:self];
}
whats wrong with the above code,it is not working,when i tilt the screen,it is not making any movemnt for the "theplayer" object.please help me to do this.
thanks in advance.
Are you sure your delegates are setup to report accelerometer information? Are you also assigning thePlayer.position in the accelerometer callback? I can't recall why but I do recall trying assignment within the callback and the results were rather stuttered and problematic. The solution for me was to have a variable the accelerometer delegate call will modify and assign the position of thePlayer inside of a tick script based on the variable update in the delegate callback.
you're not assigning the position of the player sprite. Try this:
NSLog(#"position before = %#", [NSValue valueWithCGPoint:thePlayer.position]);
thePlayer.position = ccp (pt.x+accel>0 , yLocationOfPlayer+accel<768 );
NSLog(#"position after = %#", [NSValue valueWithCGPoint:thePlayer.position]);
The logging will help you to determine if 1) the delegate method is getting fired and 2) the positions are as you are expecting.

How to notice a quick forward motion with didAccelerate deprecated?

What i want to do is read the acceleration.y and do something like:
if (acceleration.y > 0.8) {
// Do something
}
As didAccelerate is deprecated I wonder how to get the y-value:
motionManager = [[[CMMotionManager alloc] init] autorelease];
motionManager.accelerometerUpdateInterval = kUpdateInterval;
if (motionManager.accelerometerAvailable) {
[motionManager startAccelerometerUpdates];
}
else {
//this device doesn't have accelerometer notice somewhere??
}
- (void)startAccelerometerUpdates {
// READ Y-VALUE?????
}
I want to use raw accelerometer data so the app also works on 3GS. Is it possible to read the Y-value?
EDIT: the answer below is deprecated, check these posts for the right way.
Old answer:
Use a UIAccelerometer singleton instance for this, for example in your AppDelegate
//in your launching method
UIAccelerometer * accel = [UIAccelerometer sharedAccelerometer];
accel.delegate = self;
//delegate method:
-(void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration{
// use the y-property of the acceleration
}
Look at the CMMotionManager class reference and search section named "Handing Motion Updates at Specified Intervals". In the "Accelerometer" bullet, it says
Set the accelerometerUpdateInterval property to specify an update interval. Call the startAccelerometerUpdatesToQueue:withHandler: method, passing in a block of type CMAccelerometerHandler. Accelerometer data is passed into the block as CMAccelerometerData objects.
CMAccelerometerData has a reference to CMAcceleration which is a struct that holds per axis acceleration.

iPad 1 Gyroscope: roll,pitch,yaw stay zero

I'm trying to make a simple app utilizing gyroscope, where a character moves according to the rotation of the iPad 1.
My code is not working, so I tested to see the values of raw,pitch,yaw,
and they actually stay as zero however I move the device.
I'm sure iPad 1 supports CMMotionManager, so I'm not sure what's causing it...
My code is as follows
- (id) init{
if((self=[super init])){
self.isTouchEnabled = YES;
winSize = [[CCDirector sharedDirector] winSize];
[self createRabbitSprite];
self.motionManager = [[CMMotionManager alloc] init];
motionManager.deviceMotionUpdateInterval = 1.0/60.0;
if(motionManager.isDeviceMotionAvailable){
[motionManager startDeviceMotionUpdates];
}
[self scheduleUpdate];
//[self registerWithTouchDispatcher];
}
return self;
}
-(void)update:(ccTime)delta{
CMDeviceMotion *currentDeviceMotion = motionManager.deviceMotion;
CMAttitude *currentAttitude = currentDeviceMotion.attitude;
if(referenceFrame){
[currentAttitude multiplyByInverseOfAttitude:referenceFrame];
}
float roll = currentAttitude.roll;
float pitch = currentAttitude.pitch;
float yaw = currentAttitude.yaw;
NSLog(#"%.2f and %.2f and %.2f",roll,pitch,yaw);
rabbit.rotation = CC_RADIANS_TO_DEGREES(yaw);
}
Please help me out..
and thanx in advance.
(edit)
Apparently, motionManager.isDeviceMotionAvailable is returning FALSE...
which must mean that iPad 1 doesn't support CoreMotion???
Could it be something with the setting?
The iPad First generation does support CMMotionManager (as it has an accelerometer), but won't return any gyroscopic data - it doesn't have a gyroscope! You'll need to check the gyroAvailable property of a CMMotionManager instance.

iPhone accelerometer changing senstivity - Cocoa Touch

Hello
I want the sensitivity changing, for when the user moves the device. At the moment its not very sensitive, I believe its on default. I want it so its more sensitive, so when the user shakes the phone a little bit the sound plays.
Here is the code
Thanks
- (BOOL)canBecomeFirstResponder
{
return YES;
}
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
[self becomeFirstResponder];
}
- (void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event
{
if(motion == UIEventSubtypeMotionShake)
{
NSString *path = [[NSBundle mainBundle] pathForResource:#"whip" ofType:#"wav"];
if (theAudio) [theAudio release];
NSError *error = nil;
theAudio = [[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:path] error:&error];
if (error)
NSLog(#"%#",[error localizedDescription]);
theAudio.delegate = self;
[theAudio play];
}
}
First, make sure your interface adopts the UIAccelerobeterDelegate protocol.
#interface MainViewController : UIViewController <UIAccelerometerDelegate>
Now in your implementation:
//get the accelerometer
self.accelerometer = [UIAccelerometer sharedAccelerometer];
self.accelerometer.updateInterval = .1;
self.accelerometer.delegate = self;
Implement the delegate method:
- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration
{
float x = acceleration.x;
float y = acceleration.y;
float b = acceleration.z;
// here you can write simple change threshold logic
// so you can call trigger your method if you detect the movement you're after
}
The values that the accelerometer returns for x,y, and z will always be a float between -1.0 and positive 1.0. You should call NSLog and output to the console x,y, and z values so you can get a feel for what they mean. Then you can develop a simple way to detect movement.
You cannot change how the shake events work. If you need something different you will have to write your own shake-detection code based on the x/y/z forces given to you by [UIAccelerometer sharedAccelerometer]; If you set the sharedAccelerometer's delegate to your class, you can get the accelerometer's accelerometer:didAccelerate: delegate callback.
If you're trying to recreate the shake gesture, here are a few things to bear in mind:
A shake is a motion in a direction, followed by a motion in the generally opposite direction. That means you'll have to keep track of your previous acceleration vectors, so that you know when they change. So that you don't miss it, you'll have to sample from the accelerometer pretty frequently.
CGFloat samplesPerSecond = 30;
[[UIAccelerometer sharedAccelerometer] setDelegate: self];
[[UIAccelerometer sharedAccelerometer] setUpdateInterval: 1.0 / samplesPerSecond];
Then in your delegate callback:
- (void) accelerometer: (UIAccelerometer *) accelerometer didAccelerate: (UIAcceleration *) acceleration {
// TODO add this acceleration to a list of accelerations and keep the most recent (perhaps 30)
// TODO analyze accelerations and determine if a direction change occurred
// TODO if it did, then a shake occurred! Clear the list of accelerations and perform your action
}