I am working on a project which deals with an examination paper. I display only 1 question at a time on the view. After the users answers the question a second question is displayed if the user swipes towards left hand side.
I have placed a textField to display the score at each point in time. I implemented it but my score gets updated only if the user navigates to the next question.
My requirement is that as soon as the question is answered the score should be updated in the textField.
scoreField.text=[NSString stringWithFormat:#"%d",currentScore];
Is there any technique to do so whenever a question is answered? My paper has 20 questions and has 20 submit buttons so I cannot place the above code at each and every submit button action method. It would be ugly and not effective programming.
Please help if there is any way to solve my case.
Thanks in advance
If you understand your problem correctly then you don't want to set scoreField.text in every submit button handler. I am assuming that you are setting this when navigating to next question. You only need to update this when currentScore is changed. So I think it's better to create a setter for currentScore and update scoreField.text from that. Something like this:
- (void)setCurrentScore:(NSInteger)newScore {
currentScore = newScore;
scoreField.text=[NSString stringWithFormat:#"%d",currentScore];
}
And call setCurrentScore whenever you need to change the score. Or even better, you can use a setter property and write your own setter implementation.
This can be made really simple, and elegant. With a few assumptions:
There is globally accessible model object that holds the score, for example +[Examination sharedExammination].
The model object has a KVO (Key-Value-Observing) compatible property like score.
You use a custom subclass of UILabel to display the score.
With these assumptions you can let your custom UILabel register for KVO changes to to the score property and update itself automatically. The implementation of the UILabel subclass would include something like this:
-(id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
[[Examination sharedExamination] addObserver:self
forKeyPath:#"currentScore"
options:0
context:NULL];
}
return self;
}
-(void)dealloc
{
[[Examination sharedExamination] removeObserver:self
forKeyPath:#"currentScore"];
[super dealloc];
}
-(void)observeValueForKeyPath:(NSString*)keyPath
ofObject:(id)object
change:(NSDictionary*)change
context:(void*)context
{
if ([keyPath isEqualToString:#"currentScore"]) {
scoreField.text = [NSString stringWithFormat:
#"Score: %d", [object currentScore]];
} else {
[super observerValueForKeyPath:keyPath
ofObject:object
change:change
context:context];
}
}
Try this:
[self.view setNeedsDisplay];
Related
I am pretty new with Three20. I have followed ray wenderlich's nice introduction to three20 and the examples within the three20 framework. When I click on a thumbnail in a thumbnail view (subclass of TTThumbsViewController) to launch a Details view, a standard Details image view (deployed by TTPhotoViewController or its super class). I would like to use my own implementation of a Details View instead of the default. I put the following code when I initiated the subclass of TTThumbsViewController and TTThumbsViewControllerDelegate method:
- (id)initWithDelegate:(id<TTThumbsViewControllerDelegate>)delegate {
[super initWithDelegate:delegate];
return self;
}
- (void)thumbsViewController: (TTThumbsViewController*)controller
didSelectPhoto: (id<TTPhoto>)photo {
[navigationController.pushViewController:photoDetailViewController
animated:Yes];
}
But the default TTPhotoViewController view still prevail. When I put a NSLog in the delegate method. I coud see the method was called. I think there is another delegate someone already set in TTThumViewController? Can someone recommend a way to display my detail photo view? Is there another thumbs view controller I can use? Any suggestion will be greatly appreciated.
I'm really new to all of this (coding, etc.) but I'll share what I've found. By looking up the definition of ttthumbsviewcontroller, I was able to find the following method(wrong term?):-
- (void)thumbsTableViewCell:(TTThumbsTableViewCell*)cell didSelectPhoto:(id<TTPhoto>)photo {
[_delegate thumbsViewController:self didSelectPhoto:photo];
BOOL shouldNavigate = YES;
if ([_delegate respondsToSelector:#selector(thumbsViewController:shouldNavigateToPhoto:)]) {
shouldNavigate = [_delegate thumbsViewController:self shouldNavigateToPhoto:photo];
}
if (shouldNavigate) {
NSString* URL = [self URLForPhoto:photo];
if (URL) {
TTOpenURLFromView(URL, self.view);
} else {
TTPhotoViewController* controller = [self createPhotoViewController];
controller.centerPhoto = photo;
[self.navigationController pushViewController:controller animated:YES];
}
}
}
In the else statement, I've found this calls the creation of the photoviewcontroller. By recalling this method (?) in the actual body of my own code and changing the body in the else statement I was able to add a custom detail view. Further down the definition of the ttthumbsnailviewcontroller, you can find that the creatPhotoViewController calls for an initiation of the PhotoViewController so calling that method(?) in the body of the code and initializing another view also works.
If someone can explain whether or not this is a good method of doing this (I have a feeling that is not), it would be appreciated. Also why does putting the method in the body of the code override the call there.
I'm using TTLauncherView as a sort of home screen for my app and I only have one page's worth of icons. How can I make it so the TTLauncherView won't let you drag icons to "the next page"? I want to set a maximum number of pages (in this case one.)
(EDIT: long story short, I subclassed beginEditing, see the answer below.)
I see where why it adds an extra page when beginEditing is called, but I don't want to edit the framework code. (That makes it hard to update to newer versions.) I'd also prefer not to subclass and override that one method, if I have to rely on how it's implemented. (I'm not against subclassing or adding a category if it's clean.)
I tried setting scrollView.scrollEnabled to NO in the callback method launcherViewDidBeginEditing in my TTLauncherViewDelegate, but that doesn't work while it's in editing mode and I don't know why.
I tried adding a blocker UIView to the scrollview to intercept the touch events by setting userInteractionEnabled=NO, which works OK. I still have to disable the dragging of TTLauncherItems to the next page somehow.
I also tried setting the contentSize of the scrollview to it's bounds in launcherViewDidBeginEditing, but that didn't seem to work either.
Is there a better way?
Tried to block gestures:
- (void)setLauncherViewScrollEnabled:(BOOL)scrollEnabled {
if (scrollEnabled) {
[self.scrollViewTouchInterceptor removeFromSuperview];
self.scrollViewTouchInterceptor = nil;
} else {
// iter through the kids to get the scrollview, put a gesturerecognizer view in front of it
UIScrollView *scrollView = [launcherView scrollViewSubview];
self.scrollViewTouchInterceptor = [UIView viewWithFrame:scrollView.bounds]; // property retains it
UIView *blocker = self.scrollViewTouchInterceptor;
[scrollView addSubview:scrollViewTouchInterceptor];
[scrollView sendSubviewToBack:scrollViewTouchInterceptor];
scrollViewTouchInterceptor.userInteractionEnabled = NO;
}
}
For reference: TTLauncherView.m:
- (void)beginEditing {
_editing = YES;
_scrollView.delaysContentTouches = YES;
UIView* prompt = [self viewWithTag:kPromptTag];
[prompt removeFromSuperview];
for (NSArray* buttonPage in _buttons) {
for (TTLauncherButton* button in buttonPage) {
button.editing = YES;
[button.closeButton addTarget:self action:#selector(closeButtonTouchedUpInside:)
forControlEvents:UIControlEventTouchUpInside];
}
}
// Add a page at the end
[_pages addObject:[NSMutableArray array]];
[_buttons addObject:[NSMutableArray array]];
[self updateContentSize:_pages.count];
[self wobble];
if ([_delegate respondsToSelector:#selector(launcherViewDidBeginEditing:)]) {
[_delegate launcherViewDidBeginEditing:self];
}
}
I think overriding beginEditing in TTLauncherView is your best bet. Since you'd only really be touching one method (and only a few lines in that method), upgrading it when the time comes shouldn't be too bad. Since that method explicitly adds the extra page, I'm not sure how you'd get around it w/o editing that specific piece of code
As Andrew Flynn suggested in his answer, I was able to make it work by subclassing and overriding the beginEditing method to remove the extra page TTLauncherView adds when it goes into editing mode.
One problem I'm having is I can't figure out how to remove the warning I get for calling the (private) method updateContentSize on my subclass. I tried casting it to id, but that didn't remove the warning. Is it possible?
edit: I was able to remove the warning by using performSelector to send the message to the private class. (I had previously create a category method performSelector:withInt that wraps NSInvocation so that I can pass primitives via performSelector methods, which makes this very convenient.)
// MyLauncherView.h
#interface MyLauncherView : TTLauncherView {
NSInteger _maxPages;
}
#property (nonatomic) NSInteger maxPages;
#end
// MyLauncherView.m
#implementation MyLauncherView
#synthesize maxPages = _maxPages;
- (void)beginEditing {
[super beginEditing];
// ignore unset or negative number of pages
if (self.maxPages <= 0) {
return;
}
// if we've got the max number of pages, remove the extra "new page" that is added in [super beginEditing]
if ([_pages count] >= self.maxPages ) {
[_pages removeLastObject];
[self updateContentSize:_pages.count]; // this has a compiler warning
// I added this method to NSObject via a category so I can pass primitives with performSelector
// [self performSelector:#selector(updateContentSize:) withInt:_pages.count waitUntilDone:NO];
}
}
Help, I'm deperate..i can't continue my app because of this:
I have setup one message between 2 of my cocoa objective-c clases,
the main appdelegate is messaging a view through NSNotificationCenter
the view receives indeed the notification but somehow it can't update the controls visible on the view.. it's like it can't find the proper instance or something.
here's my code:
mainapp (where the appdelegate messages my view):
helloKey = #"0";
helloString = #"mymessage";
values = [NSMutableDictionary dictionaryWithObject:helloString forKey:helloKey];
[[NSNotificationCenter defaultCenter] postNotificationName:#"NewMessageNotification" object:self userInfo:values];
the function is defined in myuiviewcontoler
- (void)NewMessageNotification:(NSNotification *)notification
{
// key associated with string "Hello String"
helloKey = #"0";
// [notificaiton userInfo] returns "values"
helloFromMain = [[notification userInfo] objectForKey:helloKey];
NSLog(#"newmess=%#",helloFromMain; //this outputs mymessage , perfect right?? not quite..here's the problem
//then if I'm trying to update something visible ..it won't do IT!!!! :( :(
//tested with the debugger and it reaches this line...when the messaging occurs
[self.mybutton setTitle:#"sdsdsdasd" forState:UIControlStateNormal];
//this won't work, not it will give an error!!!
}
So what could it be the problem? nothing that is visible can be modified programaticaly when using this, and I kid of need that..
If I do a IBAction and assign it to a button of this view and do the same :
[self.mybutton setTitle:#"sdsdsdasd" forState:UIControlStateNormal];
it will update my display without no problem... modifying the title...
So what's the difference between the function that is called by the NSnotificationcenter and a function that belongs to the same view...
I tried to see the address of the self variable in both cases,, it results to be the same...
so ..basically uses the same pointer right?
still it doesn't work...
I've put another post back a few days ago..but no-one answered
Programatically created labels and images don't show on screen
It sounds very much like your NewMessageNotification: method is not being called on the main thread; UI updates must only be done from the main thread, or things won't work correctly.
The usual idiom for a situation like this is something along these lines:
- (void)NewMessageNotification:(NSNotification *)notification
{
if (![NSThread isMainThread]) {
[self performSelectorOnMainThread:#selector(NewMessageNotification:) withObject:notification waitUntilDone:NO];
return;
}
// Existing code goes here
}
It sounds like you probably have two different instances of your class, one of which is hooked up to all the stuff in the nib and one of which is registering for the notification. Try logging self in that method and you'll probably see different object addresses when it's triggered by the notification versus the button.
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.
I've got a UISearchBar in my interface and I want to customise the behaviour of the the small clear button that appears in the search bar after some text has been entered (it's a small grey circle with a cross in it, appears on the right side of the search field).
Basically, I want it to not only clear the text of the search bar (which is the default implementation) but to also clear some other stuff from my interface, but calling one of my own methods.
I can't find anything in the docs for the UISearchBar class or the UISearchBarDelegate protocol - it doesn't look like you can directly get access to this behaviour.
The one thing I did note was that the docs explained that the delegate method:
- (void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText;
is called after the clear button is tapped.
I initially wrote some code in that method that checked the search bar's text property, and if it was empty, then it had been cleared and to do all my other stuff.
Two problems which this though:
Firstly, for some reason I cannot fathom, even though I tell the search bar to resignFirstResponder at the end of my method, something, somewhere is setting it back to becomeFirstResponder. Really annoying...
Secondly, if the user doesn't use the clear button, and simply deletes the text in the bar using the delete button on the keyboard, this method is fired off and their search results go away. Not good.
Any advice or pointers in the right direction would be great!
Thanks!
Found the better solution for this problem :)
- (void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText{
if ([searchText length] == 0) {
[self performSelector:#selector(hideKeyboardWithSearchBar:) withObject:searchBar afterDelay:0];
}
}
- (void)hideKeyboardWithSearchBar:(UISearchBar *)searchBar{
[searchBar resignFirstResponder];
}
The answer which was accepted is incorrect. This can be done, I just figured it out and posted it in another question:
UISearchbar clearButton forces the keyboard to appear
Best
I've got this code in my app. Difference is that I don't support 'live search', but instead start searching when the user touches the search button on the keyboard:
- (void)searchBarTextDidBeginEditing:(UISearchBar *)searchBar {
if ([searchBar.text isEqualToString:#""]) {
//Clear stuff here
}
}
Swift version handling close keyboard on clear button click :
func searchBar(searchBar: UISearchBar, textDidChange searchText: String) {
if searchText.characters.count == 0 {
performSelector("hideKeyboardWithSearchBar:", withObject:searchBar, afterDelay:0)
}
}
func hideKeyboardWithSearchBar(bar:UISearchBar) {
bar.resignFirstResponder()
}
You could try this:
- (void)viewDidLoad
{
[super viewDidLoad];
for (UIView *view in searchBar.subviews){
for (UITextField *tf in view.subviews) {
if ([tf isKindOfClass: [UITextField class]]) {
tf.delegate = self;
break;
}
}
}
}
- (BOOL)textFieldShouldClear:(UITextField *)textField {
// your code
return YES;
}
I would suggest using the rightView and rightViewMode methods of UITextField to create your own clear button that uses the same image. I'm assuming of course that UISearchBar will let you access the UITextField within it. I think it will.
Be aware of this from the iPhone OS Reference Library:
If an overlay view overlaps the clear button, however, the clear button always takes precedence in receiving events. By default, the right overlay view does overlap the clear button.
So you'll probably also need to disable the original clear button.
Since this comes up first, and far as I can see the question wasn't really adequately addressed, I thought I'd post my solution.
1) You need to get a reference to the textField inside the searchBar
2) You need to catch that textField's clear when it fires.
This is pretty simple. Here's one way.
a) Make sure you make your class a , since you will be using the delegate method of the textField inside the searchBar.
b) Also, connect your searchBar to an Outlet in your class. I just called mine searchBar.
c) from viewDidLoad you want to get ahold of the textField inside the searchBar. I did it like this.
UITextField *textField = [self.searchBar valueForKey:#"_searchField"];
if (textField) {
textField.delegate = self;
textField.tag = 1000;
}
Notice, I assigned a tag to that textField so that I can grab it again, and I made it a textField delegate. You could have created a property and assigned this textField to that property to grab it later, but I used a tag.
From here you just need to call the delegate method:
-(BOOL)textFieldShouldClear:(UITextField *)textField {
if (textField.tag == 1000) {
// do something
return YES;
}
return NO;
}
That's it. Since you are referring to a private valueForKey I can't guarantee that it will not get you into trouble.
Best solution from my experience is just to put a UIButton (with clear background and no text) above the system clear button and than connect an IBAction
- (IBAction)searchCancelButtonPressed:(id)sender {
[self.searchBar resignFirstResponder];
self.searchBar.text = #"";
// some of my stuff
self.model.fastSearchText = nil;
[self.model fetchData];
[self reloadTableViewAnimated:NO];
}
Wasn't able to find a solution here that didn't use a private API or wasn't upgrade proof incase Apple changes the view structure of the UISearchBar. Here is what I wrote that works:
- (void)viewDidLoad {
[super viewDidLoad];
UITextField* textfield = [self findTextFieldInside:self.searchBar];
[textfield setDelegate:self];
}
- (UITextField*)findTextFieldInside:(id)mainView {
for (id view in [mainView subviews]) {
if ([view isKindOfClass:[UITextField class]]) {
return view;
}
id subview = [self findTextFieldInside:view];
if (subview != nil) {
return subview;
}
}
return nil;
}
Then implement the UITextFieldDelegate protocol into your class and overwrite the textFieldShouldClear: method.
- (BOOL)textFieldShouldClear:(UITextField*)textField {
// Put your code in here.
return YES;
}
Edit: Setting the delegate on the textfield of a search bar in iOS8 will produce a crash. However it looks like the searchBar:textDidChange: method will get called on iOS8 on clear.