Pass an array from ViewController to AppDelegate - ios

Question

I have an array of floating point values called playbackRates, set in a ViewController. I want to use these values in a function within my appdelegate. How would I access these values from within my appdelegate?
ViewController.h
#interface P15ViewController : UIViewController <GuitarStringsViewDelegate>
{
float playbackRates[6];
}
ViewController.m
- (void)viewDidLoad
{
self.guitarStringView.delegate = self;
chordNameLabel.text = chordName;
self.guitarStringView.chordName=chordName;
if([chordName isEqualToString:#"A"]){
playbackRates[0] = 1.0;
playbackRates[1] = 1.0;
playbackRates[2] = 2 * pow(2, (2/12));
playbackRates[3] = 2 * pow(2, (2/12));
playbackRates[4] = 2 * pow(2, (2/12));
playbackRates[5] = 1.0;
}
else if([chordName isEqualToString:#"B"]){
//set rates
}
else if([chordName isEqualToString:#"C"]){
//set rates
}
[super viewDidLoad];
}
appdelegate.h
#import <UIKit/UIKit.h>
#import <PAEEngine/PAEEngine.h>
#interface P15AppDelegate : UIResponder <UIApplicationDelegate>
#property (strong, nonatomic) UIWindow *window;
-(void)play:(int)index velocity:(float)velocity;
#end
appdelegate.m - player.rate needs to be set by each value in the array within the for loop in the play method
#import "P15AppDelegate.h"
#import "P15ViewController.h"
#interface P15AppDelegate ()
#property (nonatomic, strong) PAEAudioHost* host;
#property (nonatomic, strong) NSArray* channelStrips;
#property (nonatomic, strong) NSArray* filemnames;
#property (nonatomic) int nextVoice;
#end
#implementation P15AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.host = [PAEAudioHost audioHostWithNumOutputs:2];
self.filemnames = #[#"guitar-E1.wav", #"guitar-A2.wav", #"guitar-D3.wav",
#"guitar-G3.wav", #"guitar-B3.wav", #"guitar-E4.wav"];
const int numVoices = 8;
NSMutableArray* channelStrips = [[NSMutableArray alloc] initWithCapacity:numVoices];
for (int i = 0; i < numVoices; ++i)
{
PAEChannelStrip* channelStrip = [PAEChannelStrip channelStripWithNumChannels:2];
[channelStrips addObject:channelStrip];
}
self.channelStrips = [NSArray arrayWithArray:channelStrips];
PAEAmplitude* amp = [PAEAmplitude amplitudeWithNumInputs:2];
amp.input = [PAEMixer mixerWithSources:self.channelStrips];
amp.level.input = [PAEConstant constantWithValue:1.0 / numVoices];
self.host.mainMix = amp;
[self.host start];
return YES;
}
-(void)play:(int)index velocity:(float)velocity;
{
if (index >= 0 && index < self.filemnames.count)
{
PAEAudioFilePlayer* player = [PAEAudioFilePlayer audioFilePlayerNamed:self.filemnames[index]];
player.loop = NO;
player.rate - playbackRates[i]; --> **NEED TO ACCESS ARRAY HERE**
PAEAmplitude* amp = [PAEAmplitude amplitudeWithNumInputs:player.numChannels];
amp.input = player;
amp.level.input = [PAEConstant constantWithValue:velocity];
PAEChannelStrip* channelStrip = self.channelStrips[self.nextVoice];
channelStrip.input = amp;
self.nextVoice++;
if (self.nextVoice == self.channelStrips.count)
self.nextVoice = 0;
}
}
#end

Answer 1

First you'll need to write a public accessor for the playbackRates array in your UIViewController subclass named P15ViewController.
P15ViewController.h add -
- (float)playbackRateAtIndex:(NSInteger)index;
P15ViewController.m add -
- (float)playbackRateAtIndex:(NSInteger)index {
return playbackRates[index];
}
Your appDelegate needs to know of this method so import the P15ViewController.h in your P15AppDelegate.m, which I see you've already done.
Then assuming the viewController is the rootViewController of the appDelegate then you can access it with the following code.
Replace -
player.rate - playbackRates[i]; --> **NEED TO ACCESS ARRAY HERE**
With -
player.rate = [(P15ViewController*)self.window.rootViewController playbackRateAtIndex:i];
The typecast is needed so as to enable the calling of the accessor (more specifically a getter).
If a more direct access way is needed then change the getter or add another getter to return the typed address of the playbackRates array like this in the P15ViewController.m -
- (float*)playbackRatesArray {
return &playbackRates;
}
Remember to update the header file also!
And access it like this from P15AppDelegate.m, since a C array is just a pointer -
float* playbackRates = [(P15ViewController*)self.window.rootViewController playbackRatesArray];
player.rate = playbackRates[i];