IPhone SDK

From Robertjd

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Media Player Framework

Really good examples how how to use the media player framework:

http://oleb.net/blog/2009/07/the-music-player-framework-in-the-iphone-sdk/

Cocoa Specific

String programming guide

http://developer.apple.com/documentation/Cocoa/Conceptual/Strings/Articles/formatSpecifiers.html

Notifications

Posting a notification:

[[NSNotificationCenter defaultCenter] postNotificationName: @"keyboardDone" object: nil];

Observing a notification:

[[NSNotificationCenter defaultCenter] addObserver: self selector: @selector(keyboardDoneObserver:) name: @"keyboardDone" object: nil];

Handling a notification:

-(void)keyboardDoneObserver: (NSNotification*)notification {
    // do work here
}

Objective C Specific

Bool, disaster:

http://iphonedevelopertips.com/objective-c/of-bool-and-yes.html

Class type checking

if([sender isKindOfClass:[UIBarButtonItem class]]){
     //stuff
}

Convert to a string

NSString *string = [NSString stringWithFormat:@"%d", yourInteger];

http://www.idevgames.com/forum/showthread.php?t=9273

Compare Strings

if ([string1 isEqualToString: string2]) {
//do something
}

Date/Time formatting

See here for a useful date/time formatting function:

http://dblog.com.au/iphone-development/iphone-sdk-tip-function-for-getting-formatted-date-string-as-nsstring/

iPhone Simulator

Filesystem

Is here:

/Users/<you>/Library/Application Support/iPhone Simulator/User/Applications/<APP GUID>/Documents

Interface Builder

Access UI objects created in IB using tags

http://www.iphonedevsdk.com/forum/iphone-sdk-development/2947-accessing-interface-builder-object-button-code.html

Keyboard shortcuts

Command-T for the Fonts panel.

Subclassing

Make sure to create an instance of your subclass! You can't create a generic subclass and expect it to have what you need from your custom class. duh: http://forums.macrumors.com/showpost.php?p=7327494&postcount=10

Access the application delegate

[[UIApplication sharedApplication] delegate];

+ (iLaughAppDelegate *)singleton
{
   iLaughAppDelegate *delegate = (iLaughAppDelegate *)[[UIApplication sharedApplication] delegate];
   return delegate;
}

Data and Resource Management

Check that a file exists

Do this with NSFileManager:

NSFileManager *fileManager = [NSFileManager defaultManager];
if([fileManager fileExistsAtPath:fileNameString){
	return YES;
}else{
       return NO;
}

Check for Nib

if([[[NSBundle mainBundle] autorelease] pathForResource:fileName ofType:@"nib"] != nil)
{
//file found
}

Path to a resource

NSString *thePList = [[NSBundle mainBundle]  pathForResource:@"RouteList" ofType:@"plist"];  //Change YourInfo to the name of the plist file

Logging

http://iphoneincubator.com/blog/tag/nslog

http://discussions.apple.com/thread.jspa?threadID=1462712

Troubleshooting

Model view controller does not appear

I was trying to do a pushModalViewController from within viewDidLoad on a UIViewController object. This wasn't working. I then setup an IBAction method in the UIViewController object which would push the modal view controller. That worked.

The Developer Disk Image could not be mounted

An error in the organizer that occurs when the OS on the iPhone device is newer than your SDK version

Request for member currentLocation in something not a structure or union

For reasons I have yet to investigate, doing an include instead of a @class declaration solves this problem:

http://www.iphonedevsdk.com/forum/iphone-sdk-development/14218-request-member-something-not-structure-union.html

Unrecognized selector

An error looking like this:

2009-06-05 10:20:19.496 MuniReport[5683:20b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException',
reason: '*** -[UIViewController setBusType:]: unrecognized selector sent to instance 0xf52140'

Generally means "method not found in class", which usually happens when you create something in Interface Builder and don't set the appropriate class for it. See this post here:

http://forums.macnn.com/79/developer-center/370199/unrecognized-selector-sent-to-instance/

Whereas one like this:

2009-08-23 13:26:09.254 MuniReport[30664:20b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException',
reason: '*** -[Report reportImage]: unrecognized selector sent to instance 0xd2d020'

Probably means that you forgot to synthesize the property called reportImage

Keyboards

No return button for number pad keyboard:

http://discussions.apple.com/thread.jspa?messageID=7530144&tstart=0

CSS hack for defining keyboard type:

http://www.bennadel.com/blog/1197-Defaulting-To-The-Numeric-Keyboard-On-The-iPhone.htm

UIActionSheet

A quick example:

-(IBAction) getPicture{

	UIActionSheet *menu = [[UIActionSheet alloc]
						initWithTitle:@"Get image from where?"
						delegate:self
						cancelButtonTitle:@"Cancel"
						destructiveButtonTitle:nil
						otherButtonTitles:@"Take new picture",@"Get from iPhoto Library",nil];
	[menu showInView:self.view];
	[menu release];
	return;

}

Note that you can declare "nil" if you don't need a particular button.

When using with a Tab Controller

You have to add this to the window of the view if you are adding the UIActionSheet within a Tab Controller, like so:

[menu showInView:[self.view window]];

Otherwise the clickable areas for the buttons will be offset from the buttons. See here for more info:

http://discussions.apple.com/thread.jspa?threadID=1800450

A longer UIActionSheet example with delegate methods:

http://www.sonnybunny.com/site/index.php?option=com_content&view=article&id=119:uiactionsheet-delegate-methods&catid=28:iphone-dev-how-to-guides&Itemid=2

UIColor

A handy macro for setting color:

#define RGB(r, g, b) [UIColor colorWithRed:r/255.0 green:g/255.0 blue:b/255.0 alpha:1]
msgLabel.textColor = RGB(255, 251, 204);

Taken from: http://iphonedevelopertips.com/cocoa/uicolor-macros.html

UILabel

Hide/Unhide

[myLabel setHidden:YES];
[myLabel setHidden:NO];

UIImagePickerController

An example of how to pick images from the iPhoto library:

http://trailsinthesand.com/picking-images-with-the-iphone-sdk-uiimagepickercontroller/

I was hoping for a way to access the user's camera roll programmatically through some kind of class, but that doesn't seem to be possible right now:

http://stackoverflow.com/questions/818369/how-can-i-load-images-from-a-users-photo-album-on-the-iphone

http://stackoverflow.com/questions/613324/iphone-custom-uiimagepickercontroller

UINavigationController

Better traverse the navigation controller stack:

http://arstechnica.com/apple/news/2009/01/iphone-dev-tricks-manipulating-the-uinavigationcontroller-stack.ars

UITextField

Change the text field color

textField.textColor = [UIColor blackColor];

Max field length

Specify the following function in the class of the UIViewController which contains the text field, and then set the text field's delegate to be the File Owner of the view controller:

#define MAX_LENGTH 4

- (BOOL)textField: (UITextField *)textField shouldChangeCharactersInRange: (NSRange)range replacementString: (NSString *)string
{
    if (textField.text.length >= MAX_LENGTH && range.length == 0)
    {
        return NO;
    }
    else
    {
        return YES;
    }
}