I'm VERY new to Xcode but I am looking to add some extra functionality to my basic app. This functionality should log a string upon first launch. For debugging purposes I have also asked the program to output a string even if it's not first launch. I can't seem to find these messages anywhere (I'm assuming Xcode would snap to them like most IDEs). Am I doing this in the right file? The application uses the tab bar controller.
Thanks
//
// ViewController.m
//
// Created by Joel Kidd on 29/05/2013.
//
//
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
if ([[NSUserDefaults standardUserDefaults] boolForKey:#"FirstLaunch"]) {
NSLog(#"This is not the first launch.");
} else {
// Place first launch code here
NSLog(#"This is the first launch!");
[[NSUserDefaults standardUserDefaults] setBool:YES forKey:#"FirstLaunch"];
[[NSUserDefaults standardUserDefaults] synchronize];
}
// Do any additional setup after loading the view, typically from a nib.
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
All NSLog messages should appear into the debug area panel (View>Debug Area>Activate Console), also application:didFinishLaunchingWithOptions: of your app delegate would be the ideal place to check for a first launch (on your example, the code would be executed each time your controller's view would be loaded).
Related
I want to create custom back button on each page in my iOS web-view (objective-C). Can anyone please suggest me how to implement.
Thanks in Advance
I am new to iOS Web-view that is why I posted directly what I want this is my code :
#import "ViewController.h"
#interface ViewController () <UIWebViewDelegate>
#end
#implementation ViewController{
__weak IBOutlet UIImageView *logoImage;
}
- (void)viewDidLoad {
[super viewDidLoad];
self.webView.delegate = self;
NSString *urlString = #"https://www.anything.com";
NSURL *url = [NSURL URLWithString:urlString];
NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];
[self.webView loadRequest:requestObj];
self.webView.hidden = YES;
if ([_webView canGoBack]) {
[_webView goBack];
}}
- (void)webViewDidStartLoad:(UIWebView *)webView {
}
- (void)webViewDidFinishLoad:(UIWebView *)webView {
self.webView.hidden = NO;
logoImage.hidden = YES;
}
- (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error {
NSLog(#"%#", error);
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
I am passing a url of my website and I want to show a back button on every page of my application so that user can go to previous page. I have one more issue that whenever I minimise my application and opens it back from recent apps it get restarted while I want it to be resumed from the same screen
For the UIWebView, check the method - (void)goBack; out.
For the WKWebView, check the method - (WKNavigation *)goBack; and - (WKNavigation *)goBack:(id)sender; out.
UPDATE
// init the back button
[btnBack addTarget:self action:#selector(backButtonTapped:) forControlEvents:UIControlEventTouchUpInside];
- (void)backButtonTapped:(id)sender
{
[self.webview goBack];
}
Assume you have set up your webview and back button (in the navigation bar or somewhere else) in the full code.
The browser could go back when the current (tab) page has a history list and the current page url is not the first and last one.
Make sure you really want to goBack in viewDidLoad, it needs some time to finishing loading the target page you specified (https://www.anything.com) just like you do it in a browser.
The method loadRequest of webview is asynchronous, it pushes the url request to webview and returns it immediately.
Bind the webview's goBack method to your custom back button like the above code snippets.
Try to click a sample link in the initial page (https://www.anything.com), once the new page finishes loading, it could be able to goBack with satisfying [self.webview canGoBack].
Make a breakpoint in the implementation of method backButtonTapped, if needed.
Drop the logoImage or other unrelated code issues in your next question, that makes your question more clear and helpful.
I'm quite new to iOS and I hit 2 problems when writing a hello world Today extension for iOS8. I tried to create a simple today extension using the template and it works good.
However if I tried 1 of the following, the widget does not show up in Today app (there's only a title of my extension, but no body):
Delete the "hello world" label coming with the template, and add 1 new label with "hello world 2"; I notice the constraints are also automatically deleted if I'm doing this.
Uncheck "Use Auto Layout" in storyboard of today view controller, create a property of UILabel and link to the label in storyboard, then call setText on the label on viewDidLoad:
TodayViewController.m:
#interface TodayViewController () <NCWidgetProviding>
#property (nonatomic, weak) IBOutlet UILabel *cityLabel;
#end
#implementation TodayViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
[self _updateTodayView];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (void)widgetPerformUpdateWithCompletionHandler:(void (^)(NCUpdateResult))completionHandler {
// Perform any setup necessary in order to update the view.
[self _updateTodayView];
// If an error is encountered, use NCUpdateResultFailed
// If there's no update required, use NCUpdateResultNoData
// If there's an update, use NCUpdateResultNewData
completionHandler(NCUpdateResultNewData);
}
- (void) _updateTodayView {
[[self cityLabel] setText:#"Hello World 3"];
}
#end
I've been developing on Windows for years and I'm ashamed to be blocked by this issue for a whole day.
My environment:
OS X Yosemite.
Xcode 6.1
I was trying to learn UIPageViewControllers and hit an Issue which I couldn't resolve.
This is what I tried to do:
Steps:
I simply created 2 view controllers and a page view controller in
StoryBoard.
Then I added some code to the File's Owner of PageViewController to
behave as a dataSource and delegate to itself.
When I ran, things worked well.
I added some buttons, and text fields to the second view controller.
I ran, worked well.
Now I added a text view to the second view controller and ran. When I tried to write something inside the text view, the page control jittered and moved to first view controller.
Has anyone experience this ever?
#interface AMPageViewController : UIPageViewController <UIPageViewControllerDataSource, UIPageViewControllerDelegate>
#end
The implementation:
#import "AMPageViewController.h"
#interface AMPageViewController ()
{
UIViewController *mainController;
UIViewController* socController;
}
#end
#implementation AMPageViewController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:#"MainStoryboard"
bundle: nil];
mainController = (UIViewController*)[mainStoryboard instantiateViewControllerWithIdentifier: #"First"];
socController = (UIViewController*)[mainStoryboard instantiateViewControllerWithIdentifier: #"Second"];
[self setViewControllers:#[mainController]
direction:UIPageViewControllerNavigationDirectionForward
animated:NO
completion:nil];
self.dataSource = self;
self.delegate = self;
// Do any additional setup after loading the view.
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
-(UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController
{
if (viewController == socController )
return mainController;
else return nil;
}
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController
{
if (viewController == mainController )
return socController;
else return nil;
}
- (NSInteger)presentationCountForPageViewController:(UIPageViewController *)pageViewController
{
return 2;
}
- (NSInteger)presentationIndexForPageViewController:(UIPageViewController *)pageViewController
{
return 0;
}
#end
If you want to download and try the project
I've investigated a lot on this problem.
It seems a bug related to the internal (private) UIScrollView of the UIPageViewController.
If you search on StackOverflow you will find a lot of post with this problem and no solutions...
I seems that the UITextView (which is an UIScrollView and, AFAIR, has an internal UIWebView), sends some strange message to it's superviews chain, that makes the private UIScrollView of the UIPageViewController scrolling to the top-left corner.
I would have tried to block this message using method swizzling, but this is probably not ok for AppStore. So I tried other things.
The final solution is very simple: simply, embed your UITextView inside an UIScrollView!
This is a link to your project updated
If you do so, you'll solve the problem!
Try and let me know
EDIT:
How did I arrive to this solution:
An intuition.
A lot of debug and stack traces had make me think that the problem was related to a bug in the "nesting UIScrollView" system and some messages sent from the inner view to its superview.
UITextView inherits from UIScrollView and has inside an UIWebDocumentView (private) which is another UIScrollView. During the debug I saw a lot of messages (private methods) like "relayout superview" sent to the upper UIScrollView's. So, for some reason, the inner scroll view (UIWebDocumentView?) was sending a message/event to it's superview. This message/event (probably because of a bug) was not stopping to the external UITextView, and was forwarded to the UIScrollView handled by UIPageViewController.
Embedding the UITextView inside a simple UIView was not enough, because UIView forward the message to it's superview if it can't handle.
I thought: UIScrollView probably doesn't (otherwise it wouldn't simple to nest UIScrollViews), so I tried and it worked.
This is all a supposition because I stopped inspecting, I will have a more in-depth look this week.
Build target iOS-7.0.
The scrollview trick wasn't working for me. Tried to embed the textview in a scrollview through storyboard and code but no luck.
Simply delaying the call to the textview did it. Not very elegant, but its the only thing I've gotten to work so far.
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.1 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
[self.textView becomeFirstResponder];
});
}
Tested, working on my iPhone 5 and my ultra-slow iPhone4. Although its totally possible that whatever implementation detail enables the textview to become the responder could take longer than the set time. So keep in mind this isn't exactly bulletproof.
--EDIT--
Well... it's working on my iPhone 4 beater with a delay of 0.0000000000000001
you did not set before and after view controllers and also look in to first responder for socController
Start a new page based application project in Xcode
Run the project and turn some pages
Rotate the simulator or device
=> The page view conroller switches back to the first page (january)
How can I prevent step 4. ?
EDIT:
This happens only the first time you rotate after the app started in simulator/device.
I use most recent Xcode 4.5 with iOS 6.0 Simulator and iOS 6 on my testing device.
The same thing happens when I download some other sample code from blogs / etc. Maybe an iOS 6 bug?
EDIT2:
I found out that the first page view that is passed to the UIPageViewController is not dealloced until first rotation. This really looks like a bug to me.
(UPDATE FROM 2014: This seems to have been fixed in iOS7, if you start again from a new Page View application template.)
I've experienced this bug as well. It seems to kick in any time after the main view reappears. My app has several full-screen modals in it, and after those go away the same behaviour occurs.
This happens in XCode 4.5.1 and iOS6 - I 'fixed' this by re-downloading XCode 4.4 and reverting my app back to iOS5.1. Obviously not a great long-term solution. I filed this in Radar and got a note back that it was already logged.
FWIW I noticed that iBooks had this same bug in it right after iOS6 came out, but they seem to have fixed it in a recent update.
Here's how I managed to fix this problem in my app. I'm afraid it's kind of a hacky solution, but it's a quirky bug.
Context: My app is a diary (it's called Remembary) and each page is a different day's diary entry. I have a singleton class called "AppContext" that keeps track of various app-level values, such as the currently showing diary entry object, the current date, and the like. Each day's dataViewController also keeps track of its own diary entry.
The trickiest part was finding a context where I could catch that the app was showing the wrong page. It turns out that this is in [RootViewController viewDidLayoutSubviews], so I added the following to that method:
// get the currently displaying page
DataViewController *currentPage = self.pageViewController.viewControllers[0];
// check if we're showing the wrong page
if ([currentPage myEntry] != [AppContext getCurrentEntry]) {
// jump to the proper page (the delay is needed to ensure that the rotation has fully completed)
[self performSelector:#selector(forceJumpToDate:)
withObject:[AppContext getCurrentEntryDate]
afterDelay:0.5];
}
Here's the forceJumpToDate function, which basically gets a new page based on the current date and tells the pageViewController to jump to it without animating:
- (void) forceJumpToDate:(NSDate *)targetDate {
DataViewController *targetPage = [self.modelController viewControllerForDate:targetDate
storyboard:self.storyboard];
NSArray *viewControllers = [NSArray arrayWithObject:targetPage];
[self.pageViewController setViewControllers:viewControllers
direction:UIPageViewControllerNavigationDirectionForward
animated:NO
completion:NULL];
}
The user might notice a brief hiccup on the screen as the new page is forced into place, but this only happens if they would otherwise be getting the wrong page, so it's still an improvement.
This was seriously interfering with my ability to upgrade my app to iOS6, so I'm glad I finally figured it out.
Here is my solution:
// RootViewController.m
#import "RootViewController.h"
#import "ModelController.h"
#import "DataViewController.h"
#interface RootViewController ()
#property (readonly, strong, nonatomic) ModelController *modelController;
//added
#property (strong, nonatomic) DataViewController *currentViewController;
#end
#implementation RootViewController
#synthesize modelController = _modelController;
//added
#synthesize currentViewController = _currentViewController;
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
// Configure the page view controller and add it as a child view controller.
self.pageViewController = [[UIPageViewController alloc] initWithTransitionStyle:UIPageViewControllerTransitionStylePageCurl navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal options:nil];
self.pageViewController.delegate = self;
DataViewController *startingViewController = [self.modelController viewControllerAtIndex:0 storyboard:self.storyboard];
NSArray *viewControllers = #[startingViewController];
[self.pageViewController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:NULL];
self.pageViewController.dataSource = self.modelController;
[self addChildViewController:self.pageViewController];
[self.view addSubview:self.pageViewController.view];
// Set the page view controller's bounds using an inset rect so that self's view is visible around the edges of the pages.
CGRect pageViewRect = self.view.bounds;
if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad) {
pageViewRect = CGRectInset(pageViewRect, 40.0, 40.0);
}
self.pageViewController.view.frame = pageViewRect;
[self.pageViewController didMoveToParentViewController:self];
// Add the page view controller's gesture recognizers to the book view controller's view so that the gestures are started more easily.
self.view.gestureRecognizers = self.pageViewController.gestureRecognizers;
//added
self.currentViewController = self.pageViewController.viewControllers[0];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (ModelController *)modelController
{
// Return the model controller object, creating it if necessary.
// In more complex implementations, the model controller may be passed to the view controller.
if (!_modelController) {
_modelController = [[ModelController alloc] init];
}
return _modelController;
}
#pragma mark - UIPageViewController delegate methods
/*
- (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed
{
}
*/
//added
- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
self.currentViewController = self.pageViewController.viewControllers[0];
}
- (DataViewController *)currentViewController
{
if (!_currentViewController) _currentViewController = [[DataViewController alloc] init];
return _currentViewController;
}
- (UIPageViewControllerSpineLocation)pageViewController:(UIPageViewController *)pageViewController spineLocationForInterfaceOrientation:(UIInterfaceOrientation)orientation
{
if (UIInterfaceOrientationIsPortrait(orientation) || ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone)) {
// In portrait orientation or on iPhone: Set the spine position to "min" and the page view controller's view controllers array to contain just one view controller. Setting the spine position to 'UIPageViewControllerSpineLocationMid' in landscape orientation sets the doubleSided property to YES, so set it to NO here.
//deleted: UIViewController *currentViewController = self.pageViewController.viewControllers[0];
//changed to self.currentViewController
NSArray *viewControllers = #[self.currentViewController];
[self.pageViewController setViewControllers:viewControllers
direction:UIPageViewControllerNavigationDirectionForward
animated:YES
completion:NULL];
self.pageViewController.doubleSided = NO;
return UIPageViewControllerSpineLocationMin;
}
// In landscape orientation: Set set the spine location to "mid" and the page view controller's view controllers array to contain two view controllers. If the current page is even, set it to contain the current and next view controllers; if it is odd, set the array to contain the previous and current view controllers.
// deleted: DataViewController *currentViewController = self.pageViewController.viewControllers[0];
//deleted: NSArray *viewControllers = nil;
//added
NSArray *viewControllers = #[self.currentViewController];
//changed currentViewController to self.currentViewController
NSUInteger indexOfCurrentViewController = [self.modelController indexOfViewController:self.currentViewController];
if (indexOfCurrentViewController == 0 || indexOfCurrentViewController % 2 == 0) {
UIViewController *nextViewController = [self.modelController pageViewController:self.pageViewController viewControllerAfterViewController:self.currentViewController];
viewControllers = #[self.currentViewController, nextViewController];
} else {
UIViewController *previousViewController = [self.modelController pageViewController:self.pageViewController viewControllerBeforeViewController:self.currentViewController];
viewControllers = #[previousViewController, self.currentViewController];
}
[self.pageViewController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:YES completion:NULL];
return UIPageViewControllerSpineLocationMid;
}
#end
What is it you want to prevent? Do you want to prevent rotation? If that is what you want, modify the shouldAutorotateToInterfaceOrientation return value in the RootViewController.m implementation file.
When I did this, the App was able to keep the same page (month) even after rotating the device. I used the simulator and tried on both iPhone and iPad. On the iPad, in landscape mode, it showed two months at a time, but then when rotated back to portrait, still kept the first of the two months that was displayed. This was when I incremented to June. I used the default project without changing a line of code.
Today I found out that in my app I could just use the following to remove the bug (but I have no clue why).
- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration {
...
self.pageViewController.view.hidden = YES;
}
-(void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation {
self.pageViewController.view.hidden = NO;
}
I am not sure I am doing things the right way, or if I have it all hacked up.
I have a really simple test application (not document-based) I created for learning how to work with application-modal dialogs in Cocoa applications.
With the application project "TestModalDialog", I have a simple MainMenu.xib with the default view and a button, "Show Dialog", I added. I created a second XIB called TheDialog.xib that has "Cancel" and "OK" buttons. That xib has as its owner a class derived from NSWindowController called "TheDialogController"; the window outlet and delegate are connected to the controller.
Selection of "Show Dialog" on the main view will launch the dialog. Selection of "Cancel" or "OK" will dismiss the dialog. Here is the pretty simple code:
// TestModalDialogAppDelegate.h
// TestModalDialog
#import <Cocoa/Cocoa.h>
#class TheDialogController;
#interface TestModalDialogAppDelegate : NSObject <NSApplicationDelegate>
{
NSWindow *window;
TheDialogController* theDialogController;
}
#property (assign) IBOutlet NSWindow *window;
- (IBAction)showDialog:(id)sender;
#end
// TestModalDialogAppDelegate.m
// TestModalDialog
#import "TestModalDialogAppDelegate.h"
#import "TheDialogController.h"
#implementation TestModalDialogAppDelegate
#synthesize window;
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
theDialogController= [[TheDialogController alloc] init];
}
- (void)dealloc
{
if(nil != theDialogController)
[theDialogController release];
[super dealloc];
}
- (IBAction)showDialog:(id)sender
{
if(nil == theDialogController)
{
NSAlert* alert= [NSAlert alertWithMessageText:#"Dialog Error" defaultButton:nil alternateButton:nil otherButton:nil informativeTextWithFormat:#"The dialog controller was not allocated."];
[alert runModal];
return;
}
NSInteger result= [NSApp runModalForWindow:[theDialogController window]];
// Do something with result....
}
#end
// TheDialogController.h
// TestModalDialog
#import <Cocoa/Cocoa.h>
#interface TheDialogController : NSWindowController
{
// BOOL userClickedCloseOrOk; // Removed based on answer.
// Should declare a common define - just being lazy.
NSInteger userClickedOk; // Added based on answer.
UInt16 timesShown;
}
- (IBAction)showWindow:(id)sender;
- (IBAction)closeDialog:(id)sender;
- (IBAction)okDialog:(id)sender;
//- (BOOL)windowShouldClose:(id)sender; // Removed based on answer.
- (void)windowWillClose:(NSNotification*)notification; // Added based on answer.
- (void)windowDidBecomeKey:(NSNotification*)notification; // To set title when modal.
#end
// TheDialogController.m
// TestModalDialog
#import "TheDialogController.h"
#implementation TheDialogController
- (id)init
{
self = [super initWithWindowNibName:#"TheDialog"];
userClickedOk= 0; // Added based on answer.
// userClickedCloseOrOk= FALSE; // Removed based on answer.
return self;
}
-(void)dealloc
{
// Do member cleanup if needed.
[super dealloc];
}
- (void)windowDidLoad
{
[super windowDidLoad];
// Initialize as needed....
[[self window] center]; // Center the window.
}
// Does not show with runModalForWindow.
- (IBAction)showWindow:(id)sender
{
// Just playing with the window title....
++timesShown;
NSString* newTitle= [NSString stringWithFormat:#"Shown %d Times", timesShown];
[[self window] setTitle:newTitle];
return [super showWindow:sender];
}
// This method no longer used for this solution based on the answer.
//- (BOOL)windowShouldClose:(id)sender
//{
// if(!userClickedCloseOrOk) // The user did not click one of our buttons.
// [NSApp abortModal];
// else
// userClickedCloseOrOk= FALSE; // Clear for next time.
//
// return TRUE;
//}
// Added based on answer.
- (void)windowWillClose:(NSNotification*)notification
{
[NSApp stopModalWithCode:userClickedOk];
userClickedOk= 0; // Reset for next time.
}
// Note - the title will update every time the window becomes key. To do the
// update only once per modal session, a flag can be added. There might be a better
// notification to catch.
- (void)windowDidBecomeKey:(NSNotification*)notification
{
++timesShown;
NSString* newTitle= [NSString stringWithFormat:#"Shown %d Times", timesShown];
[[self window] setTitle:newTitle];
}
- (IBAction)closeDialog:(id)sender
{
//userClickedCloseOrOk= TRUE; // Removed based on answer.
//[NSApp abortModal]; // Removed based on answer.
//[[self window] performClose:self]; // Removed based on answer.
[[self window] close]; // Know we want to close - based on answer.
}
- (IBAction)okDialog:(id)sender
{
userClickedOk= 1; // Added based on answer.
//userClickedCloseOrOk= TRUE; // Removed based on answer.
//[NSApp stopModal]; // Removed based on answer.
//[[self window] performClose:self]; // Removed based on answer.
[[self window] close]; // Know we want to close - based on answer.
}
#end
I had trouble with the modality - before I put in userClickedCloseOrOk and tests, if the user hit the close button (upper-left red dot), the dialog would close but the modal session was still running.
I realize I could just leave the close-button off the dialog to start with, but with it there, is what I have demonstrated a good way to catch that scenario, or is there a better way? Or, am I doing something wrong to start with, which creates that problem for me?
Any advice would be appreciated.
NOTE - Code from the original example commented out and replaced with code based on the answer. Also added a new notification handler.
In the okDialog: and closeDialog: methods call close instead of performClose: to avoid the window calling the windowShouldClose: delegate method. That way you don't need userClickedCloseOrOk.
Also I think you want to be calling stopModalWithCode: instead of stopModal since in the app delegate you seem to be interested in the result. And you can call stopModal or stopModalWithCode: instead of abortModal because you are always in the runloop when you call it (abort is for when you are outside of the modal runloop, like in another thread or timer's runloop).
In windowShouldClose: you are doing an action (abortModal) when you should only be answering the question "should this window close". The windowWillClose: delegate method is where you should do actions if you need to.
Sheets are useful when there is one window and it tells the user they can't do anything with it until they complete whatever is in the sheet. Application-modal windows are useful when you have multiple windows that the user can't interact with until they complete whatever is in the modal window or where there is an error that involves the whole application but is not tied to the content of one window. In their HIG Apple suggests avoiding the use of Application-modal windows whenever possible.
I have actually just been struggling with the same problem and found this link :
Stopping modal when window is closed (Cocoa)