Trying to use an NSTimer - ios

Question

I'm having a problem getting an NSTimer to work, probably because I don't know how to properly use it (I've tried reading the apple documentation, it didn't help me much). I get a time off of a UIDatePicker and I want the app to call the method when that time is reached. Simple, no? So the code I have is below:
-(IBAction)SetButtonPress:(id)sender{
NSDate *date = [Picker date];
alarmTimer = [[AlarmTimer alloc] init];
[alarmTimer runTimer: Picker.date];
}
A few things now follow standards, but it still doesn't work. It still gives me a time 6 hours ahead, and when it hits that time, it doesn't do anything.
And the code for the RunTimer method of my alarmTimer class is as follows:
-(void)RunTimer: (NSDate *) date
{
NSRunLoop *theLoop = [NSRunLoop currentLoop];
[theLoop addTimer:timer forMode:NSDefaultRunLoopMode];
[timer initWithFireDate:date interval:0 target:self selector:#selector(Play) userInfo: nil repeats:NO];
}
A few things now follow standards, but it still doesn't work. It still gives me a time 6 hours ahead, and when it hits that time, it doesn't do anything.
And just in case it helps, here is the .h and .m files for the view controller:
.h:
//
// Assignment_1ViewController.h
// Assignment 1
//
// Created by Jack Schaible on 11-09-28.
// Copyright 2011 __MyCompanyName__. All rights reserved.
//
#import <UIKit/UIKit.h>
#import "AlarmTimer.h"
#interface Assignment_1ViewController : UIViewController {
UIButton *SetButton;
UIDatePicker *Picker;
UIButton *CancelButton;
NSString *time;
AlarmTimer *alarmTimer;
}
#property (nonatomic, retain) IBOutlet UIButton *SetButton;
#property (nonatomic, retain) IBOutlet UIDatePicker *Picker;
#property (nonatomic, retain) IBOutlet UIButton *CancelButton;
- (IBAction)SetButtonPress:(id)sender;
- (IBAction)CancelButtonPress:(id)sender;
#end
.m:
//
// Assignment_1ViewController.m
// Assignment 1
//
// Created by Jack Schaible on 11-09-28.
// Copyright 2011 __MyCompanyName__. All rights reserved.
//
#import "Assignment_1ViewController.h"
#import "AlarmTimer.h"
#implementation Assignment_1ViewController
#synthesize Picker;
#synthesize CancelButton;
#synthesize SetButton;
- (void)dealloc
{
[SetButton release];
[Picker release];
[CancelButton release];
[super dealloc];
}
- (void)didReceiveMemoryWarning
{
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Release any cached data, images, etc that aren't in use.
}
#pragma mark - View lifecycle
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad
{
[super viewDidLoad];
}
- (void)viewDidUnload
{
[self setSetButton:nil];
[self setPicker:nil];
[self setCancelButton:nil];
[super viewDidUnload];
[alarmTimer release];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
- (IBAction)SetButtonPress:(id)sender {
NSDateFormatter *ndf = [[NSDateFormatter alloc] init];
time = [ndf stringFromDate:self.Picker.date];
alarmTimer = [AlarmTimer alloc];
[alarmTimer init];
NSLog(#"Date is: %#", [ndf dateFromString:time]);
[alarmTimer RunTimer:[ndf dateFromString:time]];
}
- (IBAction)CancelButtonPress:(id)sender {
}
#end
And the code for the AlarmTimer class:
.h:
//
// Timer.h
// Assignment 1
//
// Created by Jack Schaible on 11-09-28.
// Copyright 2011 __MyCompanyName__. All rights reserved.
//
#import <Foundation/Foundation.h>
#import <AVFoundation/AVFoundation.h>
#interface AlarmTimer : NSObject {
NSString *time;
NSTimer *timer;
AVAudioPlayer *player;
}
-(void) RunTimer: (NSDate *)date;
-(void)Play;
-(void)CancelTimer;
#end
And finally, the .m:
//
// Timer.m
// Assignment 1
//
// Created by Jack Schaible on 11-09-28.
// Copyright 2011 __MyCompanyName__. All rights reserved.
//
#import "AlarmTimer.h"
#implementation AlarmTimer
-(id) init
{
if(self == [super init])
{
timer = [NSTimer alloc];
NSURL *url = [NSURL fileURLWithPath:[NSString stringWithFormat:#"%#/Time.mp3", [[NSBundle mainBundle] resourcePath]]];
NSError *error;
player = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:&error];
}
return self;
}
- (void) RunTimer: (NSDate *)date
{
[timer initWithFireDate:date interval:86400 target:self selector:#selector(Play) userInfo:nil repeats:NO];
NSLog(#"Date is: %#", date);
}
-(void) Play
{
[player play];
UIAlertView *aView = [[UIAlertView alloc] initWithTitle:#"Holy Chimes!" message:#"If you didn't hear that..." delegate:self cancelButtonTitle:#"Okay" otherButtonTitles:nil, nil];
[aView show];
}
-(void)CancelTimer
{
time = nil;
}
#end
Thanks a lot to anyone who can help!

Answer 1

Why do you use NSDateFormatter? try to do it like that:
alarmTimer = [AlarmTimer alloc];
[alarmTimer init];
NSLog(#"Date is: %#", self.Picker.date);
[alarmTimer RunTimer: self.Picker.date];

Answer 2

As a rule, do the +alloc and -init together: Foo *someFoo = [[Foo alloc] init];. Don't separate the calls as you've done with your timer and alarmTimer variables. The reason for this is that sometimes the initializer will return a different pointer than what you get from +alloc, and when that happens you want to be certain to store that new pointer. I don't know if NSTimer ever does that, but if so you'll have all kinds of trouble with your current code.
Don't try to reuse a timer. Once it fires, release it and create a new one when you need to.
What's all that craziness in -SetButtonPress:? You get a date from a date picker, convert it to a string, and then immediately convert that string back to a date... why?
You're using an interval of 24 hours (86400 seconds) for your timer. Are you under the mistaken impression that a timer with a long interval will wake up an app that's in the background? NSTimer relies on the run loop; when the run loop isn't running, the timer isn't working.
It'd be somewhat easier to help you if you'd stick to the usual Objective-C convention and name methods starting with lower-case characters, i.e. -runTimer: instead of -RunTimer:. The same rule applies to instance variables.