How do I initialize CMMotionManager globaly to be used by different classes? - objective-c

Question

i am trying to initialize the device motion manager in a class that contains all of my global variables to use in different classes. However i cant seem to get this working.
I have this in my global class:
// Motion Manager
CMMotionManager *motionManager;
Then set the property in a different class header file:
#property (retain) CMMotionManager *motionManager;
And on the .m file i synthetize and start the updates:
#synthesize motionManager;
motionManager = [[CMMotionManager alloc] init];
if (motionManager.deviceMotionAvailable)
{
motionManager.deviceMotionUpdateInterval = 1.0/100.0;
[motionManager startDeviceMotionUpdates];
NSLog(#"Device Started");
}
But when i call this on my third class:
motionManager.deviceMotionAvailable
It returns NO.
PD: both classes import the global class, and the third class imports the second one's header.

Answer 1

Ok it Seems i can use a singleton class to achieve this:
h file:
//
// MotionManagerSingleton.h
// Air Interface
//
// Created by MacBook on 11/12/28.
// Copyright 2011年 __MyCompanyName__. All rights reserved.
// File created using Singleton XCode Template by Mugunth Kumar (http://blog.mugunthkumar.com)
// More information about this template on the post http://mk.sg/89
// Permission granted to do anything, commercial/non-commercial with this file apart from removing the line/URL above
#import <Foundation/Foundation.h>
#import <CoreMotion/CoreMotion.h>
#interface MotionManagerSingleton : NSObject
+ (MotionManagerSingleton*) sharedInstance;
- (void)startMotionManager;
- (CMAcceleration)getCurrentAcceleration;
- (CMAttitude*)getCurrentAttitude;
- (CMAttitude*)getStartingAttitude;
- (void)setStartingAttitude: (CMAttitude*) ref;
- (bool)isDeviceReady;
- (void)destroyMotionManager;
- (NSTimeInterval) getStamp;
#end
m file:
//
// MotionManagerSingleton.m
// Air Interface
//
// Created by MacBook on 11/12/28.
// Copyright 2011年 __MyCompanyName__. All rights reserved.
// File created using Singleton XCode Template by Mugunth Kumar (http://blog.mugunthkumar.com)
// More information about this template on the post http://mk.sg/89
// Permission granted to do anything, commercial/non-commercial with this file apart from removing the line/URL above
#import "MotionManagerSingleton.h"
#implementation MotionManagerSingleton
CMMotionManager *motionManager;
CMAttitude *referenceAttitude;
bool initialized;
#pragma mark -
#pragma mark Singleton Methods
+ (MotionManagerSingleton*)sharedInstance {
static MotionManagerSingleton *_sharedInstance;
if(!_sharedInstance) {
static dispatch_once_t oncePredicate;
dispatch_once(&oncePredicate, ^{
_sharedInstance = [[super allocWithZone:nil] init];
});
}
return _sharedInstance;
}
+ (id)allocWithZone:(NSZone *)zone {
return [self sharedInstance];
}
- (id)copyWithZone:(NSZone *)zone {
return self;
}
#if (!__has_feature(objc_arc))
- (id)retain {
return self;
}
- (unsigned)retainCount {
return UINT_MAX; //denotes an object that cannot be released
}
- (void)release {
//do nothing
}
- (id)autorelease {
return self;
}
#endif
#pragma mark -
#pragma mark Custom Methods
// Add your custom methods here
- (void)startMotionManager{
if (!initialized) {
motionManager = [[CMMotionManager alloc] init];
if (motionManager.deviceMotionAvailable) {
motionManager.deviceMotionUpdateInterval = 1.0/70.0;
[motionManager startDeviceMotionUpdates];
NSLog(#"Device Motion Manager Started");
initialized = YES;
}
}
}
- (CMAcceleration)getCurrentAcceleration{
return motionManager.deviceMotion.userAcceleration;
}
- (CMAttitude*)getCurrentAttitude{
return motionManager.deviceMotion.attitude;
}
- (CMAttitude*)getStartingAttitude{
return referenceAttitude;
}
- (float)getInterval{
return motionManager.accelerometerUpdateInterval;
}
- (NSTimeInterval) getStamp{
return motionManager.deviceMotion.timestamp;
}
- (void)setStartingAttitude: (CMAttitude*) ref{
referenceAttitude = motionManager.deviceMotion.attitude;
}
- (bool)isDeviceReady{
return motionManager.deviceMotionActive;
}
- (void)destroyMotionManager{
[motionManager stopDeviceMotionUpdates];
motionManager = nil;
}
#end
and whenever I want to use it i can just declare a variable in that class header like this:
MotionManagerSingleton *Manager;
and use it like this on the m file:
Manager = [MotionManagerSingleton sharedInstance];
if ([Manager isDeviceReady]) {
NSLog(#"Device Is Ready on Drawing View Controller");
}
referenceAttitude = [Manager getStartingAttitude];

Answer 2

There is already a singleton class in every iOS App, and usually it's called AppDelegate :-)
This is because AppDelegate technically implements UIApplicationDelegate.
So, I followed this suggestion by Jonathan Hui, and it works perfectly for me.
I hope this helps, and it's not too late of an answer..