I've got a problem that I think is probably straight forward but I can't seem to wrap my head around it.
I've got a tableview that loads from an array of NSDictionaries. Each Dictionary has a title (shown in the row) and an associated nssstring representing a viewcontroller that should be pushed onto the stack when the row is selected. In other words, selecting row "A" needs to initialize an instance of "aViewController" and push it on the stack, selecting row "B" needs to initialize an instance of "bViewController" and push it on the stack, etc.
I originally just hardcoded all possible values into didSelectRow. But I'd really like to be able to dynamically generate the viewController dynamically. I found a few C++ examples of similar problems that led me to the code below. But I can't seem to get it right and am not sure I'm on the right track for an objective-c solution. Anyone have any thoughts?
Here's the didSelectRow code that's not working:
Class cls = [selectedRow valueForKey:#"viewController"];
if (cls!= nil)
{
id myNewController = [[cls alloc] init];
}
[[self navigationController] pushViewController:myNewController animated:YES];
[myController release];
Are you storing the actual Class or the class name (as an NSString) in the dictionary?
If the value you are storing in the dictionary is an NSString I don't think you can just assign Class cls = someNSString;
You can, however, do:
NSString *controllerClassName = [selectedRow valueForKey:#"viewController"];
if (controllerClassName != nil) {
id myNewController = [[NSClassFromString(controllerClassName) alloc] init];
[[self navigationController] pushViewController:myNewController animated:YES];
[myNewController release];
}
OR
Just store the Class in the dictionary instead of the NSString representation:
Related
Rookie question: I am writing a program that will generate a specific string and then display it in a text window in a different view controller. I have been testing to ensure that the code in fact generates the string using NSLog commands and I know the code is working as intended. For some reason it is not transferring across the view controller and I cant figure out why. Any help? Here is a snippet of the code:
CreateStoryViewController.m
- (IBAction)makeStory:(id)sender
{
StoryLine *myStory =[[StoryLine alloc] init];
[myStory setStory];
self.story = myStory.plot;
NSLog(#"story is %#", self.story);//this is generating the correct story string
self.displayStoryController = [[BIDDisplayStoryViewController alloc] initWithNibName:#"DisplayStoryView" bundle:nil];
[self.view insertSubview:self.displayStoryController.view atIndex:1];
}
DisplayStoryViewController.m
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
BIDCreateStoryViewController *newStory = [[BIDCreateStoryViewController alloc] init];
NSLog(#"newStory.story is %#",newStory.story);//this generates null message
self.storyDisplay.text = newStory.story;
}
This is wrong. You're instantiating a new BIDCreateViewController object inside your second view controller. This is not the same as the original BIDCreateViewController object that pushed your second BIDDisplayStoryViewController.
You need to declare a string property in your BIDDisplayStoryViewController's header file.
Something like
#property (nonatomic, retain /*or strong, if using ARC*/) NSString *storyToDisplay;
Be sure to synthesize this in your implementation file as well.
When you create BIDDisplayStoryViewController inside your first view controller, you need to do it as follows:
self.displayStoryController = [[BIDDisplayStoryViewController alloc] initWithNibName:#"DisplayStoryView" bundle:nil];
self.displayStoryViewController.storyToDisplay = self.story;
Now inside your second view controller you can access this using self.myStory.
While this will solve your problem (and please do understand that it's not my intention to be rude here), I feel that there's a lack of understanding of how iOS (and OOP in general) works.
In your viewDidLoad method you are making a whole new story. This story is totally different from the one you made in the makeStory: method. You should add a StoryLine Property to DisplayStoryViewController.h, and set that after you init your displayStoryController.
make the intended variable a property type at .h file, so the other file can access it
I am using an NSArray and alloc it to in viewDidload method.
I have two views in my app and add data to this array from these views. The total number of rows shown in a table according to [array count].
But the problem I'm facing is that when I call the view where I'm using this array from another view then this array realloc and due to this my array size again start from 0. I don't want that. I want the array size start from its last position.
So please help me to remove out this problem where I declare this array or any alternate to do this.
You need to make the array lazily loaded.
Have the view where the array is located have a getter that looks like this:
-(NSArray *)theArray {
if(theArray == nil) {
theArray = [[[NSArray alloc] init] autorelease]; //If using ARC, don't autorelease
}
return theArray;
}
In your firstView's viewDidLoad, just call the array like this:
[self theArray];
Now in your second view, call the first array like this
[firstView theArray];
I am trying to set up an object to control all of my data so it can set things up in the background to it appears my tableviews load faster than they do now etc.
This is what I am trying to achieve.
I am setting a variable in the NSObject from the secondVC when the tableviewcell is selected like this:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
//Access selected cells content (cell.textLabel.text)
UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
//Parent view logic (sends info back to the correct cell in parent view)
if (parentViewSelectedIndexPath.section == 0)
{
if (parentViewSelectedIndexPath.row == 0)
{
//Predicates restrict the values that will be returned from the query
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"%K like %#",#"MANUFACTURER",cell.textLabel.text];
NSArray *filterArray = [myDataArray filteredArrayUsingPredicate:predicate];
//[[self delegate] setManufactureSearchFields:filterArray withIndexPath:indexPath]; //This is where I pass the value back to the mainview
//Using Object
VehicleControllerNSObject *vehicleControllerNSObject = [[VehicleControllerNSObject alloc] init];
[vehicleControllerNSObject setFirstCell:filterArray];
}
//etc
At the end there you can see the method that is getting set up in the VechicleControllerNSObject which looks like this.
-(void)setFirstCell:(NSArray *)array{
manufactureSearchObjectStringFVC = [[array valueForKey:#"MANUFACTURER"] objectAtIndex:0];
NSLog(#"%#", manufactureSearchObjectStringFVC); // this prints the correct value to the console
}
As you can see this prints the correct output fine.
however I have no idea how to call manufactureSearchObjectStringFVC and pass the value it holds into the uitableviewcell that I would like to pass it in on my firstviewcontroller.
This is what I have for testing atm.
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
VehicleControllerNSObject *vehicleControllerNSObject = [[VehicleControllerNSObject alloc] init];
manufactureSearchObjectString = vehicleControllerNSObject.manufactureSearchObjectStringFVC;
NSLog(#"%#", vehicleControllerNSObject.manufactureSearchObjectStringFVC);
}
That nslog prints null..
I have three questions
1, how do I get the correct value into the first valuecontroller.
2, should I be using viewDidAppear like this?.. I think not.. how can I do this better
3, Do you think this is a good way of doing this type of thing, as in the future i would like to use the NSObjectClass to parse info, cache etc all behind the senses leaving the views to just display when the data is ready hopefully helping performance..
Any help would be hugely appreciated as I really want to learn this stuff as i know its important for me to know.
Your question is so beautifully and clearly formatted and diagrammed that it seems a shame to ask you to do a search. But here it is:
Search for Sharing Data between View Controllers
You'll find many good discussions about sharing data between view controllers.
Briefly, though, I can tell you why your code isn't working. In your tableView:didSelectRowAtIndexPath: method, you are creating (alloc/init) a new instance of your VehicleControllerNSObject class each time. Then back in your first view controller on viewDidAppear:, again you are creating (alloc/init) a whole new instance each time.
So you have multiple objects coming and going and they have nothing to do with each other. It's a bit like giving some important information to one person at a bus station and then later randomly picking some other person out and trying to retrieve that same information from her.
So one quick idea would be to create just once instance of your VehicleControllerNSObject (just an aside, that's a bit of a strange name for a class since generally all objective-c objects are descendants of NSObject anyway. I'm just going to call that VehicleController for now)
So let's say you wanted a 'sharedInstance' of VehicleController. You could add a class method to VehicleController to give you a way to easily get that one sharedInstance:
+(VehicleController*)sharedInstance {
static VehicleController *sharedInstance_ = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
sharedInstance_ = [[VehicleController alloc] init];
});
return sharedInstance_;
}
So to get that instance in methods in other classes you can just do something like :
VehicleController *sharedController = [VehicleController sharedInstance];
sharedController.someProperty = someValue;
// and then back in your first view controller, similarly:
VehicleController *sharedController = [VehicleController sharedInstance];
id someValue = sharedController.someProperty;
Again, check the search, many people have had good discussions on this. This is just one approach. I hope it at least makes sense why your code wasn't working.
Hope that helps.
To answer question 3. No.
I think that the best way to do something like this would be to use Core Data and it's NSManagedObject.
A combination of UITableViewController and NSFetchedResultsController that is feed from a Core Data sqlite backing store, if well set would feed and keep your UITableView updated.
It would be to long to describe all in here. So I will stop there.
If you don't want to go with that there is always the possibility to use a shared pointers to a mutable object or to use a singleton object to communicate information between UIViewController.
I'm trying to make a modal view which displays the champion of my app.
there's a NSMutableString variable called champ in modal view,
which is supposed to be updated by returnChamp function in main view.
the champ string is correctly set in main view,
but in modal view, the champ value appears as (null).
In fact, it seems it doesn't even go into the returnChamp function.
so apparently something wrong with my calling or implementing returnChamp,
but I have another function that does the similar, and that works fine.
could anyone please help me?
-(void) mainView{
.....
champ = [[currentPlayers objectAtIndex:playerIndex] retain];
NSLog(#"%#",champ);
modalWinner = [[winner alloc] init];
modalWinner.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
[self presentModalViewController:modalWinner animated:YES];
}
- (NSMutableString *) returnChamp{
NSLog(#"returnChamp");
return champ;
}
//in modalWinner
-(void) modalView{
..............
champName = [[NSMutableString alloc] init];
NSLog(#"%#", [(MainViewController *)self.parentViewController returnChamp]);
champName = [(MainViewController *)self.parentViewController returnChamp];
UIImage *champImage = [UIImage imageNamed:champName];
}
self.parentViewController is probably not actually a reference to your object. For some reason, it seems that the framework always insists on setting a UINavigationController as self.parentViewController - even for modals, and to the extent that it will create one if there isn't already one. This is probably going unnoticed because you're casting it to your MainViewController type.
You'll need to find a different way of making your original object available to be communicated with, or perhaps pass the appropriate value to the newly-instantiated controller before you present it.
For example, if you add a champName property to the modal class, you can do:
modalWinner = [[ModalWinnerViewController alloc] init];
modalWinner.champName = myValue; /* Set value before presenting controller */
[self presentModalViewController:modalWinner animated:YES];
There will probably be some code needed to update the UI with this value. The viewWillAppear method of the modal view controller is a good place for this as it is called by the framework immediately before the view is presented.
Note that this property-based approach could be used to keep a reference to your intended parent object, as well. And see here for a different approach to solving a similar problem.
I have a function here that upon completing a single round, if your score is higher than either a default score entry or a newly placed high score then it will swap its data with your data and push everything else down. removing the last entry from the list. currently this is just one exchange and for functions sake I'm going to hard code it and then refactor it later.
My main problem is that when I set up a text input view to capture the players name execution continues immediately without the players input and crashes the game. I commented out the line that sets the text because I have a default value in place just in case any attempt that I try to make fails. How can I get Execution to wait for a moment while input is taken? Would I have to set up a delegate method? If so I'm still a bit confused by delegates. I could set it up to work but I don't understand it, so I wouldn't be able to do any other special custom tasks with it. I've worked on it for a while and got no further...
-(void)saveData:(ScoreKeep *)stats{
NSMutableDictionary *swap = [[NSMutableDictionary alloc]init];//used for swaping entries
NSString *filePath = [self pathOfFile];
NSLog(#"Writing to %#", filePath);
if ([[NSFileManager defaultManager]fileExistsAtPath:filePath]) {
NSLog(#"Loading previous dictionary to save...");
dataDictionary = [NSMutableDictionary dictionaryWithContentsOfFile:filePath];
if ([dataDictionary objectForKey:#"1"]) {
NSMutableDictionary *highScore = [dataDictionary objectForKey:#"1"];
if ([stats.score intValue] > [[highScore objectForKey:#"SCORE"] intValue]) {
NSLog(#"You Win! score: %# highscore: %#", stats.score,[NSNumber numberWithInt:[[highScore objectForKey:#"SCORE"] intValue]] );
stats = [[ScoreKeep alloc] initWithNibName:#"Scorekeep" bundle:nil];
NSLog(#"Setting up name entry");
[self.view addSubview:stats.view]; //New view is added so that the player can input data(Assume it is complete);
//stats.nameTag = setName.nameTag;//This line is executed before the new view is dismissed causing an error to occur
[stats setupDictionary]; // It just goes down hill from here if the previous line is uncommented
[dataDictionary setObject:stats.sComponents forKey:#"1"];
}else {
NSLog(#"You Lose: %# highscore: %#", stats.score,[NSNumber numberWithInt:[[highScore objectForKey:#"SCORE"] intValue]] );
}
NSLog(#"Got first place entry");
}else {
NSLog(#"Initilizing Score");
}
}else{
NSLog(#"Creating new dictionary to save...");
dataDictionary = [[NSMutableDictionary alloc]init];
}
[dataDictionary writeToFile:filePath atomically:YES];
}
Help would greatly be appreciated. If more information is needed I'd be happy to provide.
by the way ScoreKeep is an object that contains a dictionary and a function to create a dictionary such that it can set any values I need and package them into sComponents(the dictionary to be entered into the main savefile)
#import <UIKit/UIKit.h>
#import <Foundation/Foundation.h>
#class omphalosUtility;
#pragma mark -
#pragma mark Saving data
#pragma mark -
static inline void poop(){
NSLog(#"POOP");
}
I'm going to try making a utility file that works independently of the app so that I Can update files and perform other universal operations such as saving when needed. Its a step in a direction that i'd like to take.
If i get it right, (The code is really nasty, man...) your problem is that you are trying to present a View Controller with the wrong way.
Correct me if i'm wrong, is ScoreKeep is a ViewController? if so, you have to name it properly. that's for a start.
Second, you cant present another view controller only by adding its "view" property to the current view controller's View Hierarchy. that way the view will not respond properly to the events.
the correct way to to what you'r trying to do is by presenting the ScoreKeep ViewController modally.
there is no other right way to do this without using delegation. you will have to acquire this technique.
Your view controller that responsible for getting the name from the user need to have a way to tell it's master view controller that the user entered a name. and that is achieved through delegation.
What you should do:
Basically you create a protocol called something like "NamePrompterViewControllerDelegate"
that will have at least one method that will be called when the user will done entering his name.
Your ScoreKeepViewController should have an instance variable that implemented the protocol (Look at the apple documentation on protocols for assistance)
Your main view controller (the one that contains the method you added) then should implement the protocol you created, and set itself as the delegate of ScoreKeep like that:
stats = [[ScoreKeep alloc] initWithNibName:#"Scorekeep" bundle:nil];
stats.delegate = self;
For more info on presenting and dismissing ViewControllers modally you should read the documentation at Apple Documentation
I hope i helped you, there is just a lot to cover and it hardly can be done by writing an answer.
Feel free to ask more for clearance.