I'm a noob on objective C so I'm sorry if I don't use the right terms to describe my problem but I need a hand and SO is my least resource!
I'm trying to interface an Arduino balance with my mac with an objective C software in which I've got a Nib file and a controller one: to do that I use ORSSerialPort which runs ok.
I'm experiencing some problems while loading a NSCombobox (the one with I make the user able to choose the serial port) after the user interface loading: in my controller class I have a method called "InitializeView" which calls this method:
-(void)RefreshSerialPortsInComboBox{
//Clear all existing elements
for (int i = 0; i < [self.serialPortsComboBox numberOfItems]; i++) {
[self.serialPortsComboBox removeItemAtIndex:i];
}
//Reload the serial ports list
NSArray *availableSerialPorts = [[NSArray alloc] initWithArray:[serialPortManager availablePorts]];
//Reload the Combobox elements with the new serial ports list
for (int i = 0; i < [availableSerialPorts count]; i++) {
[self.serialPortsComboBox addItemWithObjectValue:[[availableSerialPorts objectAtIndex:i] valueForKey:#"_path"]];
[self InsertTextInBufferTextView:#"Elemento creato...\n"];
}
}
The problem is that if I call this method in my controller object's init method, this doesn't work and the combobox items list is still empty: take note that the controller is instantiated by Interface Builder.
I tried to link the above method to a button and it works so it seems to be a matter of loading priority, it seems that I'm going to call the method before loading the ui objects or making them ready to be worked on...or maybe something else but I don't know what.
Can someone help me?
Another similar alternative just for completeness is to implement the method awakeFromNib, this method is called for all objects represented in a nib file. Its defined in the informal protocol NSNibAwaking
You should call this method in loadView method:
- (void)loadView {
[super loadView];
[self RefreshSerialPortsInComboBox];
}
Your code doesn't work because view and all IBOutlets haven't not initialized in "init" method yet.
Related
I whant to handle all my contacts in another class. I do not realy know how to do it, so I am doing it like this:
HandleContact is sub class of SKNode
-(void)didBeginContact:(SKPhysicsContact *)contact {
HandleContact *handleContact = [[HandleContact alloc]
initWithBodyA:contact.bodyA.node bodyB:contact.bodyB.node
scene:self];
}
Everything works as aspected, but i am getting this error:
Unused variable 'HandleContact'
So how should I do it in correct way ? (Maybe i should use another type? )
Your current code is a memory leak. Every time a contact is registered, you instantiate a HandleContact class. If you want to have a class to handle your contacts, I suggest you instantiate it at the beginning of your code and keep a reference to it. Some place like (void)didMoveToView:(SKView *)view
The question you need to ask yourself is why do you need a class to handle your contacts? You can call different methods from within didBeginContact if you are looking to organize your code.
-(void)didBeginContact:(SKPhysicsContact *)contact {
uint32_t collision = (contact.bodyA.categoryBitMask | contact.bodyB.categoryBitMask);
if (collision == (CategoryAlpha | CategoryBeta))
[self myMethod1];
}
I have an NSComboBox in my mainmenunib file.
I have created an outlet of combobox "cb" and made a connection of it with my delegate
I also connected delegate and datasource with my delegate.
-(void)applicationDidFinishLaunching:(NSNotification *)aNotification
{ arr=[NSMutableArray arrayWithObjects:#"a",#"b",#"c",#"d",#"e",#"f", nil];
[cb reloadData];
}
-(NSInteger)numberOfItemsInComboBox:(NSComboBox *)aComboBox{
return arr.count;
}
-(id)comboBox:(NSComboBox *)aComboBox objectValueForItemAtIndex:(NSInteger)loc{
return [arr objectAtIndex:loc];
}
But when I run the application data is not coming in combobox.
Please help me out as i am new to cocoa programming.
Thanks in advance.
Your approach seems reasonable on the face of it, though using a mutable object as an instance variable is often ill-advised (for reasons wholly unrelated to your issue here, and which we needn't get into at this stage).
There are two things that jump out as possible issues:
1) Are you using ARC? If not, arr is going to disappear from under you because -arrayWithObjects returns an autoreleased object and you have nothing retaining it. If you are using ARC (the default for new project on Lion, I believe), this doesn't apply to you. Plus I would expect you would crash, not just get no data.
2) More likely, you forgot to -setUsesDataSource:YES, which is the flag that tells NSComboBox whether to look at its data source or to use the internal contents approach that #JustinBoo supplied. I believe this defaults to NO, which would cause your exact problem. I don't have Interface Builder in front of me at the moment, but IIRC there is a "uses data source" checkbox that you can check to enable this attribute.
You can add objects using -addItemWithObjectValue to Your NSComboBox like this:
arr = [NSMutableArray arrayWithObjects:#"a",#"b",#"c",#"d",#"e",#"f", nil];
for (int i = 0; i < [arr count]; ++i)
{
[cb addItemWithObjectValue:[arr objectAtIndex:i]];
}
You can see NSComboBox Reference for more information.
Is there a way to add a category to a class whose header file you can't access?
For testing purposes, I want to add a category to UITableViewCellDeleteConfirmationControl, but the class is (as far as I can tell) part of a private framework.
How can I do that?
Elaboration (per mihirios's request):
I am trying to extend the Frank testing framework to simulate tapping the confirmation button (the big red "Delete" button) that appears when you try to delete a UITableViewCell. Frank adds a tap method to UIControl. For some reason, Frank's usual way of tapping a control does not work for the UITableViewCellDeleteConfirmationControl class (which subclasses UIControl).
I've create a workaround. I added a category to UITableViewCell, with the following method.
- (BOOL)confirmDeletion {
if (![self showingDeleteConfirmation]) {
return NO;
}
UITableView *tableView = (UITableView *)[self superview];
id <UITableViewDataSource> dataSource = [tableView dataSource];
NSIndexPath *indexPath = [tableView indexPathForCell:self];
[dataSource tableView:tableView
commitEditingStyle:UITableViewCellEditingStyleDelete
forRowAtIndexPath:indexPath];
return YES;
}
This finds the table's data source and invokes its tableView:commitEditingStyle:forRowAtIndexPath: method, which (according to the documentation for UITableView) is what the system does when the user taps the confirmation button.
This works, but I would prefer to make UITableViewCellDeleteConfirmationControl appear to be a tappable button by adding a tap method to it, overriding Frank's default one. The tap method would find the cell that contains the confirmation button, then invoke [cell confirmDeletion].
When I try to declare a category for UITableViewCellDeleteConfirmationControl, the compiler complains that it "can't resolve interface 'UITableViewCellDeleteConfirmationControl'."
When I try to use the header file that someone generated using class-dump, the linker complains that it can't find the symbol _OBJC_CLASS_$_UITableViewCellDeleteConfirmationControl.
For testing purposes, you can always get the class object using NSClassFromString and then use the class_replaceMethod runtime method to do whatever you need. See the Objective-C Runtime Reference for details.
As far as i know you can not use a Category, but you could add the methods manually during runtime.
A Possible way to do this is, to create a new class, implement the methods you want to, and send this methods to UITableViewCellDeleteConfirmationControl using the appropriate objc-runtime functions. There are some things to take care of, like storing the original functions for later use in case of overloading, also in your 'category'-class you have to pay attention when you want to call super, as this will not work, you have to use objc-runtime function objc_msgSendSuper instead.
As Long as you don't need to call super this will do fine:
#import <objc/runtime.h>
#import <objc/message.h>
void implementInstanceMethods(Class src, Class dest) {
unsigned int count;
Method *methods = class_copyMethodList(src, &count);
for (int i = 0; i < count; ++i) {
IMP imp = method_getImplementation(methods[i]);
SEL selector = method_getName(methods[i]);
NSString *selectorName = NSStringFromSelector(selector);
const char *types = method_getTypeEncoding(methods[i]);
class_replaceMethod(dest, selector, imp, types);
}
free(methods);
}
a good point to call the method is in main.m, for example:
#autoreleasepool {
implementInstanceMethods([MyCategory class], NSClassFromString(#"UITableViewCellDeleteConfirmationControl"));
return UIApplicationMain(argc, argv, nil, NSStringFromClass([YourAppDelegate class]));
}
But i don't know why you not just move the confirmation handling in the controller-class.
As long as the compiler can (eventually) link to the class in question you can create a category for it. The more important question will be how to design the category since it seems you do not have access to the source for the original class.
I'm creating a game that uses cards.
I have an AppController class with one instance in the nib.
The AppController instance has an NSArray instance variable called wordList.
On init, the nib's instance of AppController generates a new GameCard.
Every gamecard has an array of words containing 5 words selected at random from the the list in AppController.
Because the list is large, I'd like to read it into memory only once. Therefore, I want only one instance of AppController, as a singleton class. Every time a new GameCard is created from within AppController, it should access that same singleton instance to retrieve the wordlist.
So basically, I need a singleton AppController that creates GameCards, where each GameCard has a reference to the original AppController.
I'm not sure how to implement this. Sorry if the explanation was confusing.
A code example I found online follows (http://numbergrinder.com/node/29)
+ (AppController *)instance
{
static AppController *instance;
#synchronized(self) {
if(!instance) {
instance = [[AppController alloc] init];
}
}
return instance;
}
But when I tried to do something with it in a GameCard instance through the code below, my application took forever to launch and Xcode told me it was loading 99797 stack frames.
AppController *controller = [AppController instance];
It sounds like an infinite loop. Make sure that -[AppController init] isn't calling +[AppController instance].
Why does every card need a reference to the app controller?
If it's just to access its words, it's simpler to let each card own its words directly. Make a new method named initWithWords: the designated initializer for the GameCard class. Initialize each card with the array of its five words, and have the card own that array for its lifetime.
Removing the cards' references to the app controller would resolve the infinite loop that Tom astutely detected.
Also, if no word should appear on two cards at once, remember to take that into account when drawing from the app controller's Great Big Array Of Words, and when destroying cards (you may or may not want the words to go back into the pile for future cards).
It sounds like you're on the right track. I've never tried to put a reference to a singleton in a nib file, though. You may want to create a separate singleton class that maintains a copy of the data (DataManager, maybe?), and then call it from within your instance of AppController to fetch the words.
You may find that putting a singleton within a nib (using the code for a singleton in Stu's post) works just fine, though. Good luck!
It looks like you may be calling your class instance method from within your init method. Try something like this:
static AppController* _instance = nil;
- (id)init
{
// depending on your requirements, this may need locking
if( _instance ) {
[self release];
return _instance;
}
if( (self = [super init]) ) {
_instance = [self retain];
// do your initialization
}
return self;
}
+ (AppController*)instance
{
if( _instance ) return _instance;
else return [[AppController alloc] init];
}
This makes sure that only one instance of AppController is ever available and also that it's safe to allocate it as well as getting a copy through the instance class method. It's not thread safe, so if it's going to be accessed by multiple threads, you should add some locking around the checks to _instance.
The normal way to create an AppController/AppDelegate is to add a custom NSObject to your MainMenu/MainWindow.xib file. Set the class to be AppController. Link your UIApplication/NSApplication delegate reference to your AppController object. Then you can get your single AppController with either
(AppController*)[NSApp delegate];
or
(AppController*)[[UIApplication sharedApplication] delegate];
You never have to create it with alloc/init because it will be created when your application is launched. You don't have to worry about making it a singleton because no one will ever try to create another one. And you don't have to worry about how to access it because it will be the delegate of the UIApplication/NSApplication object.
All that said, if you need a global variable holding an array of words, then forget about the AppController and make a new singleton object which holds/reads the array. In which case you just need:
+ (NSArray *)sharedWordListArray
{
static NSArray *wordList;
if( !wordList ) {
wordList = [[NSMutableArray alloc] init];
// read array
}
return wordList;
}
If you really need thread safety, then simply call [WordList sharedWordListArray] from your app delegate's applicationDidFinishLaunching: method before starting any threads, or add an NSLock if you really want to defer the loading to later, but often its better to take the load time hit at the start of the program rather than unexpectedly when the user takes some later action.
Given
#interface Canvas:NSView {
NSNumber * currentToolType;
...
}
declared in my .h file
and in the .m file
- (id)initWithFrame:(NSRect)frame {
self = [super initWithFrame:frame];
if (self) {
currentToolType=[[NSNumber alloc]initWithInt:1];
}
return self;
}
and further down
-(void)mouseUp:(NSEvent *)event
{
NSLog(#"tool value in event: %d",[currentToolType intValue]);
//rest of code
}
-(NSBezzierPath *)drawPath:(NSRect)aRect
{
NSLog(#"tool value in draw: %d",[currentToolType intValue]);
//rest of drawPath method code that uses the value of currentToolType in a switch statment
}
-(IBAction)selectToolOne:(id)sender
{
[currentToolType release];
[currentToolType = [[NSNumber alloc]initWithInt:0];
}
-(IBAction)selectToolTwo:(id)sender
{
[currentToolType release];
[currentToolType = [[NSNumber alloc]initWithInt:1];
}
The action methods are the only place where currentToolType is changed. But, for some reason, it seems to be a different instance of currentToolType in the mouseUp. I did not write (or synthesize) accessors for the var as it is used only by itself. I noticed that initWithFrame is called twice - I'm assuming it's for the parent window and the NSView?
What am I missing?THANKS!
This is an XCode generated Document based app using COCOA and Obj-C. I'm new at both.
You mention that initWithFrame: is called twice. Your initWithFrame: should only be called once (unless you happen to have two Canvas views).
Is it possible you have the Canvas view in your nib/xib file and are also creating another in code (with alloc/initWithFrame:)?
In which case you have two Canvas objects. You probably have one hooked up to your controls and the other one is in the window (and thus responding to the mouseUp: and it is giving you the same value every time).
If you have the Canvas view setup in IB, you can fix this problem by removing your code that is creating the second one.
You've probably run in to a special case: NSNumber could have cached instances to represent commonly-used numbers.
Two observations, though:
You're wasting a whole lot of memory using NSNumber when you could be simply using NSIntegers or maybe an old-fashioned enumerated type, completely avoiding the object overhead.
You never actually showed your code for when you look at the instances of NSNumber; without it, there's not really enough information here to answer your question.