Is there a way to identify which object is calling the draw method.
Creation:
joint.model = [[Box alloc] init];
The calling code:
[joint.model draw];
The draw method (within Box class):
-(void)draw
{
glBindVertexArrayOES(_boxVAO);
glDrawArrays(GL_TRIANGLES, 0, 7055*3);
}
How can i receive the joint object in my draw method?
If more class info is necessary i can attach, but i did not assume since theres not much more.
The model object needs to have a pointer back to joint in order to use it in the -draw method. So you need to either modify the Box class to have a pointer to whatever type joint is, or if Box is defined by a framework you're using, you need to subclass it. So you could do either:
#class Box {
Model* model; // Or whatever type model is.
}
Or if that's not an option, you could do this:
#class BetterBox : Box {
Model* model; // Or whatever type model is.
}
And make sure that model.joint is created like this:
model.joint = [[BetterBox alloc] init]; // or [[Box alloc] init] if you modified the Box class
[model.joint setModel:model];
Then in your draw method, you can simply access model like this:
- (void)draw
{
[model someMethod];
//... etc. ...
}
Related
I'm using ReactiveCocoa framework at my app for the power using MVVM design pattern.
So for every Controller, I have a ViewModel. and the Controller is binded to his ViewModel.
UIButton binding will look like so:
#implementation HomeController
-(void) bindViewModel {
self.viewHeader.buttonSide.rac_command = self.viewModel.execiteFullPortfolio;
}
It all works well, But when i would like to pass parameters to the ViewModel, I'm not sure what is the right way to do so...
Say I have a UICollectionView of Stocks, and every click on a specific stock, I would like to navigate to thats stocks profile page.
That logic should be done at the ViewModel, But how do i get the stock passed with the RACCommand?
What I'm currently doing is :
#implementation HomeController
-(void) bindViewModel {
__unsafe_unretained HomeController *weakSelf = self;
self.viewPortfolioPusherView.scrollGainView.blockSelect = ^ (STStock *stock){
weakSelf.viewModel.selectedStock = stock;
[weakSelf.viewModel.executeGoToStock execute:[RACSignal empty]];
};
}
#implementation HomeViewModel
-(void) initialization {
self.executeGoToStock = [[RACCommand alloc] initWithSignalBlock:^RACSignal *(id input) {
dispatch_async(dispatch_get_main_queue(), ^{
[weakSelf moveToSelectedStock];
});
return [RACSignal empty];
}];
}
-(void) moveToSelectedStock {
[self stockProfileControllerLazy];
self.stockProfileController.stock = self.selectedStock;
[Navigator pushController:self.stockProfileController fromController:[self.delegate controller]];
}
I'm sure this is not best practice! So I'm asking, What is??
Thanks .
Why not just pass the STStock instance into the call to execute on the command, rather than an empty signal?
[weakSelf.viewModel.executeGoToStock execute:stock];
Then:
self.executeGoToStock = [[RACCommand alloc] initWithSignalBlock:^RACSignal *(STStock *stock) {
dispatch_async(dispatch_get_main_queue(), ^{
[weakSelf moveToSelectedStock:stock];
});
return [RACSignal empty];
}];
You obviously need to modify moveToSelectedStock to take a parameter as well. However, I'd go a bit further an implement an RACCommand on your Navigator that does that. Furthermore, I'd make a separate view model for an instance of STStock rather than a collection. So, when you select a stock, it might look something a little more like this:
StockViewModel *viewModel = [[StockViewModel alloc] initWithStock:stock];
[[Navigator pushViewModel] execute:viewModel];
This obviously omits a few details. For example, my navigator maps view model classes to controller classes. When a view model is pushed, it creates the corresponding controller, and binds the view model to it.
I am writing an app which is a sort of dictionary - it presents the user with a list of terms, and when clicked on, pops up a dialog box containing the definition. The definition itself may also contain terms, which in turn the user can click on to launch another definition popup.
My main app is stored in 'myViewController.m'. It calls a custom UIView class, 'CustomUIView.m' to display the definition (this is the dialog box that pops up). This all works fine.
The text links from the CustomUIView then should be able to launch more definitions. When text is tapped in my CustomUIView, it launches another CustomUIView. The problem is, that this new CustomUIView doesn't have access to the hash map which contains all my dictionary's terms and definitions; this is only available to my main app, 'myViewController.m'.
Somehow, I need to make my hash map, dictionaryHashMap, visible to every instance of the CustomUIView class. dictionaryHashMap is created in myViewController.m when the app opens and doesn't change thereafter.
I don't wish to limit the number of CustomUIViews that can be opened at the same time (I have my reasons for doing this!), so it would be a little resource intensive to send a copy of the dictionaryHashMap to every instance of the CustomUIView. Presumably, the solution is to make dictionaryHashMap a global variable.
Some of my code:
From myViewController.m:
- (void)viewDidLoad
{
self.dictionaryHashMap = [[NSMutableDictionary alloc] init]; // initialise the dictionary hash map
//... {Code to populate dictionaryHashMap}
}
// Method to pop up a definition dialog
- (void)displayDefinition:(NSString *) term
{
NSArray* definition = [self.dictionaryHashMap objectForKey:term]; // get the definition that corresponds to the term
CustomUIView* definitionPopup = [[[CustomUIView alloc] init] autorelease]; // initialise a custom popup
[definitionPopup setTitle: term];
[definitionPopup setMessage: definition];
[definitionPopup show];
}
// Delegation for sending URL presses in CustomUIView to popupDefinition
#pragma mark - CustomUIViewDelegate
+ (void)termTextClickedOn:(CustomUIView *)customView didSelectTerm:(NSString *)term
{
myViewController *t = [[myViewController alloc] init]; // TODO: This instance has no idea what the NSDictionary is
[t displayDefinition:term];
}
From CustomUIView.m:
// Intercept clicks on links in UIWebView object
- (BOOL)webView: (UIWebView*)webView shouldStartLoadWithRequest: (NSURLRequest*)request navigationType: (UIWebViewNavigationType)navigationType {
if ( navigationType == UIWebViewNavigationTypeLinkClicked ) {
[myViewController termTextClickedOn:self didSelectTerm:request];
return NO;
}
return YES;
}
Any tips on how to make the dictionaryHashMap visible to CustomUIView would be much appreciated.
I have tried making the dictionaryHashMap global by doing the following:
Changing all instances of 'self.dictionaryHashMap' to 'dictionaryHashMap'
Adding the line 'extern NSMutableDictionary *dictionaryHashMap;' to CustomUIView.h
Adding the following outside of my implementation in myViewController.m: 'NSMutableDictionary *dictionaryHashMap = nil;'
However, the dictionaryHashMap remains invisible to CustomUIView. As far as I can tell, it actually remains a variable which is local to myViewController...
It's not resource-intensive to pass around the reference (pointer) to dictionaryHashMap. A pointer to an object is only 4 bytes. You could just pass it from your view controller to your view.
But I don't know why you even need to do that. Your view is sending a message (termTextClickedOn:didSelectTerm:) to the view controller when a term is clicked. And the view controller already has a reference to the dictionary, so it can handle the lookup. Why does the view also need a reference to the dictionary?
Anyway, if you want to make the dictionary a global, it would be more appropriate to initialize it in your app delegate, in application:didFinishLaunchingWithOptions:. You could even make the dictionary be a property of your app delegate and initialize it lazily.
UPDATE
I didn't notice until your comment that termTextClickedOn:didSelectTerm: is a class method. I assumed it was an instance method because myViewController starts with a lower-case letter, and the convention in iOS programming is that classes start with capital letters. (You make it easier to get good help when you follow the conventions!)
Here's what I'd recommend. First, rename myViewController to MyViewController (or better, DefinitionViewController).
Give it a property that references the dictionary. Whatever code creates a new instance of MyViewController is responsible for setting this property.
Give CustomUIView properties for a target and an action:
#property (nonatomic, weak) id target;
#property (nonatomic) SEL action;
Set those properties when you create the view:
- (void)displayDefinition:(NSString *)term {
NSArray* definition = [self.dictionaryHashMap objectForKey:term];
CustomUIView* definitionPopup = [[[CustomUIView alloc] init] autorelease]; // initialise a custom popup
definitionPopup.target = self;
definitionPopup.action = #selector(termWasClicked:);
...
In the view's webView:shouldStartLoadWithRequest: method, extract the term from the URL request and send it to the target/action:
- (BOOL)webView: (UIWebView*)webView shouldStartLoadWithRequest: (NSURLRequest*)request navigationType: (UIWebViewNavigationType)navigationType {
if ( navigationType == UIWebViewNavigationTypeLinkClicked ) {
NSString *term = termForURLRequest(request);
[self.target performSelector:self.action withObject:term];
return NO;
}
return YES;
}
In the view controller's termWasClicked: method, create the new view controller and set its dictionary property:
- (void)termWasClicked:(NSString *)term {
MyViewController *t = [[MyViewController alloc] init];
t.dictionary = self.dictionary;
[t displayDefinition:term];
}
Create a class that will be used as singleton. Example.
You Should always keep your data in separate class as the mvc pattern suggest and that could be achieved by using a singleton class for all your dictionary terms and accesing them from every custom view when needed.
I'm having a problem with either typecasting or object scope. I'm getting an uncaught exception:
// Create the object here so that it's scope is outside the `if` statement, right?
searchTableViewController *newViewController;
if (rowSelected) {
// Typecast the object to a searchTableViewController
(searchTableViewController *)newViewController ;
// Initialize and Allocate
newViewController = [[searchTableViewController alloc] initWithSearchBar:NO grouped:NO];
}else{
// Typecast the global object to a personViewController
(personViewController *)newViewController;
// Initialize and Allocate
newViewController = [[personViewController alloc] init];
}
// Act on the object: create a data model object and store it as a property, etc.
newViewController.myDataModel = [[dataModel alloc] initWithSelected:selectedField delegate:newViewController];
I have 2 similar ViewControllers searchTableViewController and personViewController. So I want to be able to instantiate either one or the other, using the same name, that way the rest of my code can act on the viewController using common properties and such.
This is causing a Terminating due to uncaught exception and regardless it seemed like the wrong way to do it anyway. I need help either in the typecasting department or I need help understanding how to declare the scope of these objects properly so I can work with them in and outside of the if statement.
Update
The easiest thing would be for me to write my code as follows. How can I declare, allocate and instantiate an object within an if statement and then have it accessible outside?:
if (rowSelected) {
searchTableViewController *newViewController = [[searchTableViewController alloc] initWithSearchBar:NO grouped:NO];
}else{
personViewController *newViewController = [[personViewController alloc] init];
}
// This will probably give an error since newViewController is not in the proper scope.
newViewController.myDataModel = [[dataModel alloc] initWithSelected:selectedField delegate:newViewController];
You want to declare your newViewController as the common subclass of the two objects you're possibly allocating. Probably UIViewController.
UIViewController *newViewController;
if (rowSelected) {
// Initialize and Allocate
newViewController = [[SearchTableViewController alloc] initWithSearchBar:NO grouped:NO];
}else{
// Initialize and Allocate
newViewController = [[PersonViewController alloc] init];
}
And the cast operation isn't doing anything when you use it in-place like that.
Edit - if both of those classes have common properties, like dataModel, then you can avoid warnings by creating a common base class that derives from UIViewController and which contains those properties. You'd then change the declaration of your view controller variable in the first line above to match the intermediate base class.
Later Edit — if you don't want to create an intermediate base class, you can do the following (newViewController still must be declared as a UIViewController):
if([newViewController respondsToSelector:#selector(setMyDataModel:)]) {
DataModel *dataModel = [[dataModel alloc] initWithSelected:selectedField delegate:newViewController];
[newViewController performSelector:#selector(setMyDataModel:) withObject:dataModel];
}
RE: Your Edit
id newViewController;
if (rowSelected) {
newViewController = [[searchTableViewController alloc] initWithSearchBar:NO grouped:NO];
}else{
newViewController = [[personViewController alloc] init];
}
// This will probably give an error since newViewController is not in the proper scope.
newViewController.myDataModel = [[dataModel alloc] initWithSelected:selectedField delegate:newViewController];
As an example, when I'm using an NSMutableDictionary, I know it inherits all the methods of NSDictionary, but how can I know/trust that it has overridden the behavior of those methods if I want to use NSDictionary methods (such as +dictionaryWithObjectsAndKeys) to create my mutable dictionary instance?
More generally, is it the Framework's responsibility to make sure subclasses don't blindly inherit methods that can potentially break instances of the subclass if used? Or is it the coder's responsibility to know not to use them? If Square inherits from Rectangle, and via inheritance I can call
Square *newSquare = [[Square alloc] init];
[newSquare setWidth:3 andHeight:6]; //instead of -(void)setSide:(int)side
I've "broken" the square and other methods which depend on width being equal to height will not work now. What are the rules of the game?
The rule would be only expose what you would allow to be override it means, put on your interface what is really public. When necessary explicitly state that when overriding an specific method call at some point [super methodName].
On your example you would override the method - (void)setWidth:(int)width andHeight:(int)height, and you would like to throw an error if width != height. Or you could also throw an error and force the user to only use - (void)setSide:(int)side.
For example you could do:
// If you want to test and accept cases when width == height
- (void)setWidth:(int)width andHeight:(int)height {
NSAssert(width == height, NSLocalizedString(#"This is a Square. Width has to be height.", nil));
[super setWidth:width andHeight:height];
// Or
[self setSide:width];
}
// Or if you want to completely prohibit the usage of the method
- (void)setWidth:(int)width andHeight:(int)height {
NSAssert(NO, NSLocalizedString(#"This is a Square! Please use - (void)setSide:(int)side method.", nil));
}
If you would like to throw some errors and warnings at compilation time, you could use on the declaration of your methods, some of the macros defined on NSObjCRuntime.h.
I wouldn't trust the parent convenience method to call your inheriting init method. For example, that dictionary method could be defined as:
+ (id)dictionaryWithObjectsAndKeys:...
{
return [[[NSDictionary alloc] initWithObjectsAndKeys:...] autorelease];
}
If that method is defined that way then it won't be even be aware of your implementation.
You'd have to create your own convenience method. Something like would be in your MyDictionary implementation:
+ (id)myDictionaryWithObjectsAndKeys:...
{
return [[[MyDictionary alloc] initWithObjectsAndKeys:...] autorelease];
}
--
Also...
You probably should inherit Rectangle from Square. Inheritance is additive. You can describe Square with one size (width), but for Rectangle you have two sizes (width, height).
I want to initialize an instance of one of the subclasses of a superclass depending on the arguments to init:
[[Vehicle alloc] initWithItinerary: shortWay]; // returns a bicycle
[[Vehicle alloc] initWithItinerary: longWay]; // returns a car
I can't find examples of code like this. I wonder if this is not idiomatic in Objective C, or I simply am not looking in the right places.
You could do this via a custom init method, but it'd be kind of tedious (you'd have to invoke [super init], but then call [self release], etc...). It'd be much simpler to create a class method on Vehicle and use that as your factory method. For example:
+ (id) vehicleWithItinerary:(id)someItinerary {
if ([someItinerary isAShortWay]) {
return [[[Bicycle alloc] initWithItinerary:someItinerary] autorelease];
} else if ([someItinerary isAMediumWay]) {
return [[[RocketPack alloc] initWithItinerary:someItinerary] autorelease];
} else if ([someItinerary isALongWay]) {
return [[[Car alloc] initWithItinerary:someItinerary] autorelease];
}
return nil;
}
Look at [UIButton buttonWithType:] for an example of how Apple does this. Instead of init, they use a static method of the base class to allocate an instance of the appropriate derived class.
You can also pass around Class objects. Maybe the itinerary knows the Class or class name to allocate. You can do something like this:
[[[itinerary classToAllocate] alloc] initWithItinerary:itinerary];
or
[[NSClassFromString( [itinerary classNameToAllocate] ) alloc] initWithItinerary:itinerary];
You are allowed to release self and create a new object in init, although this is rarely used. Just watch out for recursion.
-(id) initWithItinerary:(Itinerary *)inItinerary {
[self release]; // super init never called - safe if you wrote super classes
self = [[[inItinerary classToAllocate] alloc] init];
self.itinerary = inItinerary;
return self;
}
This is called a class cluster. Several Cocoa classes work this way, including NSArray and NSString. The object returned from NSArray's init methods is never the same object that received the message. It's not that common outside of Cocoa, though, just because it's usually more complicated than people want to bother with. Basically, you figure out what actual class you want to use in your initializer, create an instance of that class, release yourself and return the other instance.
You might want to add an enum to the header file:
typedef enum {Bike, Car, JetPack
} vehicleType
That way your initWithItinerary: method can simply be:
if(VehicleType == Bike)
{
//do bike stuff
}
else if(VehicleType == Car)
{
//do car stuff
}
Why not have a method as part of the "way" that gives you a vehicle of the appropriate type for the way. e.g.
e.g.
// Somwhere before you use them. Car and Bicycle are subclasses of Vehicle
[shortWay setAppropriateVehicleType: [Bicycle class]];
[longWay setAppropriateVehicleType: [Car class]];
// when you need a vehicle
Vehicle* vehicle = [[[shortWay appropriateVehicleType] alloc] init];