Iam a newbiew to iPhone development. Version of my SDK is 2.2
In my code, UIViewController is used to change view dynamically once the app is launched, a method in the UIViewController is called to know which view should be initialized along with parameters, which goes to a 'switch-case' and assign a view to current view according to the parameter, like this:
case 1:
currentView = [[View01 alloc] init];
break;
case 2:
currentView = [[View02 alloc] init];
break;
and outside the switch-case:
[self.view addSubview:currentView.view];
I wonder f can pass a parameter along with initialization, like iniWithNibName or so? I need this because have to manipulate in the leaded view, according to the view from which its called.
Thanks.
One way to approach this is to modify your View01 and View02 classes to include an initWithParam: initialiser.
i.e. add
- (id) initWithParam:(NSString *)myParam;
to the #interface section and add
- (id) initWithParam:(NSString *)myParam {
if (self = [self init]) {
// handle or store 'myParam' somewhere for use later
}
return self;
}
to the #implementation section. Notice how the initWithParam: message internally calls the existing init. Obviously you could change the type, or number of parameters passed in as required.
Another approach would be to provide a property on your view class, so you could do something like the following:
currentView = [[View01 alloc] init];
currentView.myParam = #"SomeValue";
Which approach works the best will depend somewhat on your particular application needs.
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 working on an iPhone app. Initially, I had my pickerview in the same screen so this was just a one page app. After skinning it i realized that i want the pickerview on it's own separate page. So i did that. However, my pickerview originally would update uilabels and other objects on that same page. How can I have my pickerview access those objects from it's new view?
- (IBAction)ShowPickerAction:(id)sender {
if (self.theView == nil) {
theView = [containerView initWithNibName:#"containerView" bundle:nil];
theView.parentView = self;
}
self.theView.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
[self presentModalViewController:self.theView animated:YES];
}
That is the method I am using to call my new view. But line 3 of the above code gives me the error "No known class name for selector initWithNibName:bundle". I think that error is related to something that i did wrong in my header file. My new class is called containerView. So i did this in my header:
#interface ViewController : UIViewController {
containerView *theView;
But that gives me the error "Unknown type name containerView" even though i do have a class named containerView!!
Look into uiappdelegate protocol or try passing values to through a static function to the previous page.
Use a delegate to pass information back and forth to the view object that instantiatrd the picker view. You want to keep your code coupling as loose as possible, especially if you might like to drop it into your next project. Using a delegate and/or blocks are some of the best ways.
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'm pretty new to the objective-c language (less than three months) but it is something that i really need to understand.
Suppose there is a controller (in a iOS environment) that manages a table view for input data from the user. The table must have editable cells and some features to make the value selection easier, for example a button that shows a popover with the possible values for a field.
Suppose there is a field to store country names. The popover first shows a list of continents; when the user selects a continent, the controller of the popover must show the countries of the previews selected continent.
Now, this popover appears in many places in the app so it will be nice if I can encapsulate it for later use. What i will expect for this popover is something like this:
...
#protocol MyPopoverDelegate<NSObject> {
-(void)didSelectCountry:(NSString *)countryName;
{
...
MyPopoverController *dataSelector = [[MyPopoverController] alloc] init];
dataSelector.dataType = CountryDataType;
dataSelector.delegate = self;
[dataSelector show];
[dataSelector release];
...
The problem here is the line [dataSelector release] because the code for managing the popover must stay alive until the country is selected. That's means the dataSelector variable must be a property of the caller class and that sucks.
The question then is:
How can i organize situations like this to have a reusable controller?
Thanks
Edited after vodkhang answer:
Ok, that's a good one, but dataSelector still is a property.
What if i do:
#implementation MyPopoverController
- (id)init {
...
[self retain];
...
}
- (void)popoverControllerDidDismissPopover: (UIPopoverController *)popoverController {
...
[delegate didFinishSelectingCountry:countryName];
[self release];
}
#end
I never see this behavior in objective-c, i feel that this is not the idea.
Why is it wrong?.
One of the way you can do for delegate method is to have:
MyPopOverDelegate
- (void)didFinishSelectingCountry:(NSString *)countryName popOver:(MyPopOver *)popOver;
Caller.m
// the caller
- (void)viewDidLoad {
MyPopoverController *dataSelector = [[MyPopoverController] alloc] init];
dataSelector.dataType = CountryDataType;
dataSelector.delegate = self;
[dataSelector show];
}
- (void)didFinishSelectingCountry:(NSString *)countryName popOver:(MyPopOver *)popOver {
// finish stuff
[popOver release];
}
This way is used a lot like NSUrlConnection, UIImagePickerController
If you want some unique object reusable across an entire app from anywhere in the view hierarchy, you can make it a property of the app delegate, and let the app delegate own it (retain it when live, release it during memory warnings, etc.).
A self retained object may eventually run into problems if you ever port your code to a garbage collected environment.
following situation:
in a TTTableViewController i added some Cells with URLs.
they are opening a class with #"tt://photos" for example. this works quite fine.
the first thing is, i saw some urls in TT Examples like #"tt/photos/1". is it possible to fetch this "1" in my photos class and say, for example okay, please open picture one, ore is this only another URL that was declared in TTNavigatior to open a specific Class?
the other thing is: is it possible to forward an object to the linked class?
clicking a cell opens #"tt://photos" (the linked class in my TTNavigator)
working with normal tableviews i can overwrite my init method and send an object with my initialize method, is this also possible by clicking my TTItems?
thanks!
figured it out myself, for those who need it:
First (passing "subURLs" in your navigator map)
navigating to an URL with #"tt://photos/firstphoto" is possible, you can fetch the "firstphoto" like this:
//Prepare your Navigator Map like this
[map from:#"tt://photos/(initWithNumber:)" toViewController:[PhotoVC class]];
In your PhotoVC you can access this Number:
-(void) initWithNumber: (NSString*)number {
NSLog(#"%#",number);
}
calling your View Controller with this url would look:
PhotoVC* controller = [[PhotoVC alloc] initWithNumber:#"1"];
[navigationController pushViewController:controller animated:YES];
[controller release];
Second (passing objects in an TTTableViewController)
its a bit tricky, but you dont have to Subclass anything.
first, nil the URL in the TableItem
[TTTableLink itemWithText:#"TTTableLink" URL:nil]
in your TTTableViewController write down this method
- (void)didSelectObject:(id)object atIndexPath:(NSIndexPath*)indexPath {
TTURLAction *urlAction = [[[TTURLAction alloc] initWithURLPath:#"tt://photos"] autorelease];
urlAction.query = [NSDictionary dictionaryWithObject:#"firstphoto" forKey:#"photo"];
urlAction.animated = YES;
[[TTNavigator navigator] openURLAction:urlAction];
}
now in your your PhotoVC you need something like this
- (id)initWithNavigatorURL:(NSURL*)URL query:(NSDictionary*)query {
if (self = [super init]) {
NSLog(#"%#",query);
}
return self;
}
and you are done ;)
I was trying to implement choise's answer, learned a lot, and eventually had to get the callouts showing up and keep the implementation with many urls simple, so here's what i did.
Keep URL in the TableItem,
Use this code in the TTTableViewController subclass.
- (void)didSelectObject:(id)object atIndexPath:(NSIndexPath*)indexPath {
NSLog(#"Its url is %#", [object URL]);
TTURLAction *urlAction = [[[TTURLAction alloc] initWithURLPath:(NSString *)[object URL]] autorelease];
urlAction.query = [NSDictionary dictionaryWithObject:self.user forKey:#"user"];
urlAction.animated = YES;
[[TTNavigator navigator] openURLAction:urlAction];
}
- (BOOL)shouldOpenURL:(NSString*)URL {
return NO;
}
That "shouldOpenURL:" was discovered looking through TTTableViewController, I tried it out, and it worked. Now the table view is not opening a duplicate view, and there are callouts!
Thanks choise!
Although choice's answer works for multiple params when u are creating the TTURLAction in code it is not very useful when u want to embed links to view controllers in your TTStyledLabel.One solution to that is to use multiple params in a single string.
<a href='app://view2/param1=value1¶m2=value2&...'>LabelName</a>
if you want the code to parse such urls and get the params please feel free to send me a message and I will send you my parser classes.
(or you can build your own with NSScanner!)
Also dont forget to escape the &s otherwise TTStyledLabel would not like it!
You don't need to run this on current version 1.0.6.2 for TTTableViewController. The "URL" option is working as expected. If it's not working for you, then your URL is broken or your are calling the wrong function on your ViewController. The function you have to call through URL must return an id (be a constructor for a ViewController) of a ViewController. Then it'll work as expected.
I'll changed the example form choise to be like TTNavigator expect it to be.
Add a mapping, which TTNavigator will use to navigate:
//Prepare your Navigator Map like this
[map from:#"tt://photos/(initWithNumber:)" toViewController:[PhotoVC class]];
Create a TTTableLink (or TTStyledText, or other) with an URL set, which should mach your map:
[TTTableLink itemWithText:#"TTTableLink" URL:#"tt://photos/1"]
Add this to your PhotoVC to be called by TTNavigator on the given URL
-(id) initWithNumber: (NSString*)number {
if (self = [super init]) {
self.title = #"Some Title";
NSLog(#"%#",number);
}
return self;
}
You don't need to overwrite the function didSelectObject, as the TTNavigator will call your ViewController through defined constructor function tt://photos/(initWithNumber:)