Following a tutorial exactly, I created files that extend UITableViewController. The problem is that his uitableviewcontroller.m files is filled with pre written code (like the viewDidLoad), while mine is completely blank! Both our uitableviewcontroller.h files all have the code of
#import <UIKit/UIKit.h>
#interface ChemTable : UITableViewController
#property (strong,nonatomic)NSMutableArray *Chemarray;
#end
For learning purpose the auto-generated method are of least use(its perfectly ok even if You remove it). even you can create app without them....."viewDidLoad" is the one very necessary method that runs when the view is loaded, but when you go for real apps you will surely use some of auto-generated methods.
Extra -->I think you also also should see this:
ViewDidLoad - Called when you create the class and load from xib. Great for initial setup and one-time-only work
ViewWillAppear - Called right before your view appears, good for hiding/showing fields or any operations that you want to happen every time before the view is visible. Because you might be going back and forth between views, this will be called every time your view is about to appear on the screen
ViewDidAppear - Called after the view appears - great place to start an animations or the loading of external data from an API.
ViewWill/DidDisappear - Same idea as the WillAppear.
ViewDidUnload/Dispose - Available to you, but usually not necessary in Monotouch. In objective-c, this is where you do your cleanup and release of stuff, but this is handled automatically so not much you really need to do here.
Related
I have studying how to use IKImageView in my app. I downloaded the following demo from Apple site.
https://developer.apple.com/library/mac/samplecode/IKImageViewDemo/Introduction/Intro.html#//apple_ref/doc/uid/DTS10004049
One thing I do not understand is: This project has only implemented a Controller class.
#interface Controller : NSObject
{
...
I do not understand how does it work at all. If I create a new project in XCode, it will usually generate an AppDelegate class which implements NSApplicationDelegate interface.
I do not know if I understand the mechanism correctly.
Does the following steps describe how it works?
1) In info.plist it specifies the main bundle is MainMenu.xib.
2) the Window is binded to the Controller like so
3) When the application starts, it loads the Windows from the MainMenu.xib and the Controller class takes over the windows interaction from there.
It's really old sample code. It predates Xcode project templates generating an app delegate for you.
Back then, early Xcode and ProjectBuilder (the old name for it)
Left it up to you to do that.
Lots of older sample code has this sort of thing. As long as things get kickstarted by nib loading, magic happens, objects are instantiated and connected
If you have a simple controller that inherits from NSObject and it has a proxy in you main nib file, it will get created. If you also connect its proxy as delegate to some view or control in the nib, all of that happens.
You don't technically need an object that is the delegate of you NSApplication object. But in reality it is a good best practice and any non trivial app will have that and a lot more.
There's a lot of magic that happens when the C function NSApplicationMain() is called at the launch of your app.
The old and in many ways out if date book Cocoa in a Nutshell covers this well.
Yeah you pretty much describe how it works and what it's doing.
It's relying on the fact that NSApplicationDelegate is an informal protocol and it doesn't declare that Controller conforms to it and is using the NIB to kick-start the app.
I am working with cocos2d and CoreData. I have imported "AppDelegate.h" but I can't create an object from it. I would think that all I would do is:
AppDelegate *delegate;
When I do this it get an error saying AppDelegate is not defined. The AppDelegate .h and .m files are next to the main file.
Also, when I try to write to a file I don't get an error but it does not write.
The boiler plate code created by XCode (I'm assuming you are using XCode) will create an NSManagedObjectContext for you called *managedObjectContext. If you need to create other objects that are going to interact with your core data model (such as a view controller), you simply pass in that managedObjectContext object as an argument (or link it to a property in your custom class) and interact with it in your custom class. It's worth noting that it's not good practice to be passing around an AppDelegate object in your app. Your app delegate should be at the foundation of your code base and not treated as a typical class. There are definitely times when you will want (or need) to pass the app delegate as an object or reference it in IB, but typically your app will launch in your
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
method and you will launch your primary view controller from there.
Some things in core data also require the persistent store coordinator (such as retrieving managed object ID's), so you may need to pass that in as well. If you need some help working with Core Data, there are a bunch of great articles and books on the subject. I recommend reading as many as you can, since Core Data can be difficult to comprehend at first. It helped me to read a bunch of tutorials at first since everyone explains it a little differently.
Here's a great recent tutorial written on Bindings, Core Data, and working with the app delegate to get you started: http://www.raywenderlich.com/21752/how-to-use-cocoa-bindings-and-core-data-in-a-mac-app
In Cocos2d 2.0, AppDelegate is renamed to AppController
AppController *app = (AppController*)[UIApplication sharedApplication].delegate;
When you first create an Application in XCode, at it's lowest level it creates the AppDelegate.h/.m and a MainWindow.xib
Once you start modifying the Xib to best suit your design needs - is it best practice to move away from the AppDelegate as the initial Controller or is it always better to create a new WindowController to use with the MainWindow.xib ??
Fritzables
The AppDelegate class cannot be used as a view controller, if that's what you're asking. Your AppDelegate class should be creating an instance of your main View Controller, which loads your main .xib file. Unless you're referring to defining the main Xib in your target configurations, but that's pretty old school.
Are you constrained by the version of iOS you need to support? Because you could avoid using .xib files altogether by using storyboards if you can use iOS 5.0 and up.
Well good question. To me app delegate always has been a initial step to define a project that I create. There are many use for delegates but that is another subject. If you look at the apple doc's related to this subject (over view section) in the following link, there is a great explanation of what is the function of the app delegate there. To answer the question you ask, it is always a good practice to leave the app delegate and create a new controller and execute whatever function you want in there. Here is the link to apple do's and I hope it clears up everything for you my friend. Happy coding.
http://developer.apple.com/library/ios/ipad/#documentation/uikit/reference/UIApplicationDelegate_Protocol/Reference/Reference.html
i have been working on moving one of my apps away from the "shared appdelegate" process which seems to be frowned up, despite its over whelming use. i have been attempting to setup protocol methods for what i want to do but am having zero luck. my question is, can you even have lets say a single viewcontroller send delegate requests to multiple classes? from what im finding out it doesn't seem like you can. which doesn't make sense because i thought that was the whole point of delegates and protocols with mvc. now just to clarify, i know you can have a single viewcontroller act as the delegate for multiple other viewcontrollers. but that's not what i am asking. for a simple example, lets say you have apples flip-utility template. the "done" button just calls a delegate method to the mainvc to dismiss it. now lets say we added a new class called...
#interface NewClass : NSObject <TheOtherDelegate>
and it had a delegate method...
- (void)doSomething
{
NSLog(#"The Delegate did something...");
}
can we have a button on the flipsideviewcontroller, that we wanted to call that delegate method, but still keep the "done" button call to the delegate method on the mainviewcontroller that dismisses it?
that being said, i put together a quicky project just to see if it would work and it doesn't. i came across an "answer" that says you have to instantiate the class first you want to be the delegate...
NewClass *myDelegate = [NewClass alloc] init]
[fillInMethodHere setDelegate:myDelegate];
not sure why it got a correct answer check, because needless to say it doesn't work. is there something i am missing? i scoured ib to see if there is some "delegate" connection somewhere but i couldn't find anything.
on a side note, as i was working in my working project, i read a suggestion about removing the #import and adding #class. again, that broke all kinds of things. the strange thing is before doing that, what i had so far was working and building fine. when i removed the new #class and un-commented the #import. xcode all of a sudden gave me an error "cannot find protocol deceleration for..." but yet, it worked seconds earlier. i would up having to remove the protocol code and re-add it for it to work again. very starge.
any help would be appreciated. everything iv read in docs, google, stack, etc that say something should work, don't in an actual project.
A "delegate" isn't some fancy object. It's simply a synthesized property of type id called delegate. If you wanted to, you could have an arbitrary number of properties that all conformed to the same protocol. Then when you wanted to issue a callback, you would just address all of them:
[self.mydelegateA doSomething];
[self.mydelegateB doSomething];
etc.
You could also have an NSMutableArray property that you could add objects to, and then use [self.myMutableArrayOfDelegates makeObjectsPerformSelector:#selector(doSomething)].
Finally, there's always the route of NSNotificationCenter (not to be confused with push notifications) is a class that provides an inter-object messaging system. Many objects can register for a message that any other object can send.
Please see the Apple's documentation for more information. Click Here.
Regardless of the fact that this is OS X documentation, it's still quite good at explaining things visually: click here.
Here's an example of simply changing the name of the delegate property: click here
And here's an example of adding another protocol and a second delegate: click here
Finally, here's an example that builds on the previous two and has a third delegate that also conforms to the same protocol: click here
I have written a few apps for the iphone now, but they are all written in what I consider to be a lazy, unstructured way.
I have started a new project and have created several Objective-C classes (subclass of NSObject). the problem I have is getting the logic correct in my head. My structure is as follows
viewController.h
viewController.m
plotPoints.h
plotPoints.m
handleFeeds.h
handleFeeds.m
So the main file is the view controller and I include in it's header file the other classes. My problem is that in the other class files, eg plotPoints.m - if I try to refer to a variable I set in the view controller, it says it's not set. I have included the viewcontroller in the plotPoints.h file - but still it doesnt work.
what is best practice for separating code in this way? In this example, I have webservice feeds which I want to handle in one class, then process those results in another and handle the main UI in the view controller.
Thanks for any information.
I say the Controller shouldn't be referenced by your - as I understand - external classes (plotPoints and handleFeeds, by the way these should definitely begin with an uppercase character).
Actually, it should be the exact opposite, your viewController should be using methods and properties of your external classes. PlotPointsand HandleFeeds should not have to refer to instance variables of your Controller, let it pass them as arguments for you methods instead.