I know that in order to show/hide the throbber on the status bar I can use
[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
But my program sends comm requests from many threads, and I need a location to control whether the throbber should be shown or hidden.
I thought about a centralized class where every comm request will register and this class will know if one-or-many requests are currently transferring bytes, and will turn the throbber on, otherwise - off.
Is this the way to go? why haven't Apple made the throbber appear automatically when networking is happening
Try to use something like this:
static NSInteger __LoadingObjectsCount = 0;
#interface NSObject(LoadingObjects)
+ (void)startLoad;
+ (void)stopLoad;
+ (void)updateLoadCountWithDelta:(NSInteger)countDelta;
#end
#implementation NSObject(LoadingObjects)
+ (void)startLoad {
[self updateLoadCountWithDelta:1];
}
+ (void)stopLoad {
[self updateLoadCountWithDelta:-1];
}
+ (void)updateLoadCountWithDelta:(NSInteger)countDelta {
#synchronized(self) {
__LoadingObjectsCount += countDelta;
__LoadingObjectsCount = (__LoadingObjectsCount < 0) ? 0 : __LoadingObjectsCount ;
[UIApplication sharedApplication].networkActivityIndicatorVisible = __LoadingObjectsCount > 0;
}
}
UPDATE: Made it thread safe
Having some logic in your UIApplication subclass singleton seems like the natural way to handle this.
//#property bool networkThingerShouldBeThrobbingOrWhatever;
// other necessary properties, like timers
- (void)someNetworkActivityHappened {
// set a timer or something
}
- (void)networkHasBeenQuietForABit
// turn off the indicator.
// UIApplcation.sharedApplication.networkActivityIndicatorVisible = NO;
}
Related
I have two independent delegate methods in a class.
- (void)delegateMethod1:(id)data {
self.data = data;
}
- (void)delegateMethod2 {
[someClass sendData:self.data];
}
Now, this works fine sometimes but the other times, delegateMethod2 gets called before delegateMethod1.
I need to know how to manage this elegantly so that the line: [someClass sendData:self.data]; gets called only when both delegateMethod1 and delegateMethod2 have been called.
I know I can do it by using a variable to set to something on each delegate call but there has to be an elegant way to do this.
Any help?
Remembering which delegate has been called seems the easiest and cleanest solution to me.
But you can make it symmetric by moving the check to a separate method, so that
is does not matter which delegate is called first:
- (void)checkIfDataCanBeSent {
if (self.method1called && self.method2called) {
[someClass sendData:self.data];
}
}
- (void)delegateMethod1:(id)data {
self.method1called = YES;
// ...
[self checkIfDataCanBeSent];
}
- (void)delegateMethod2 {
self.method2called = YES;
// ...
[self checkIfDataCanBeSent];
}
(I have assumed that all delegate methods are called on the main thread, otherwise
one would have to add some synchronization.)
I believe, using a indicative variable to be the most elegant way to get over this. But this variable has to be kept in the delegate caller object.
Pseudo-type explanation
#interface DelegateCaller
{
BOOL hasCalled1stMethod;
}
#property(nonatomic,weak) id delegate;
#end
#implementation DelegateCaller
-(void)in_some_process_1
{
[self.delegate delegateMethod1]; //call
hasCalled1stMethod = YES; //set indicator
}
-(void)in_some_process_2
{
if(hasCalled1stMethod)
{
[self.delegate delegateMethod2]; //call
hasCalled1stMethod = NO; //reset indicator for reuse, if required.
}
}
#end
This way you'll not have to maintain any variable in the delegate itself, because the regulation of calling is maintained in the caller-object itself.
Another case:
If the delegateMethod1 is called from some object1 and the delegateMethod2 is called from some other object2, then again the indicative variable method is the most elegant way (in this limited scenario)
Pseudo-type explanation:
#interface ClassDelegateObject //aka the callee
{
BOOL hasCalledMethod1;
}
#end
#implementation ClassDelegateObject
-(void)delegateMethod1:(NSData*)data
{
self.data = data;
hasCalledMethod1 = YES; //set the indicator.
}
-(void)delegateMethod2
{
//here relying on the self.data!=nil will not be fruitful
//in case the self.data is not nil and hold some previous garbage data then
//this logic will fail.
if(hasCalledMethod1)
{
[someClass sendData:self.data];
hasCalledMethod1 = NO; //reset the variable for reuse if required.
}
}
#end
I would suggest that you rethink how the code works. Maybe you can check if there is no data and if so send it once it is ready:
- (void)delegateMethod1:(id)data {
self.data = data;
if (self.dataShouldBeSentWhenReady) {
[self sendData];
}
}
- (void)delegateMethod2 {
if (self.data) {
[self sendData];
} else {
[self setDataShouldBeSentWhenReady:YES];
}
}
- (void)sendData {
[self setDataShouldBeSentWhenReady:NO];
[someClass sendData:self.data];
}
I have an iOS app with about 50 views. I want to perform some operation after every 5th screen that the user visits. I know I can create a sort of global counter variable and update that on viewDidLoad of each view, and if count is 5, then perform that operation, and reset that counter variable. Is there a better, more efficient way of doing this? Also looking ahead, if I require to alter something, I would rather do it in a single file than all of my views. Would really appreciate some inputs on this.
I would create a singleton class to keep track of your counter logic, create a base class for all of your view controllers and then make your call to the counter singleton in the viewDidLoad of your base class.
I think something like this would work for you:
#interface ViewCountManager()
#property(nonatomic) NSInteger viewCount;
#end
#implementation ViewCountManager
#define kOperateOnCount 5
+(ViewCountManager *)viewCountManager
{
static ViewCountManager *viewCountManager = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
viewCountManager = [[self alloc] init];
});
return viewCountManager;
}
-(BOOL)shouldPerformOperation
{
BOOL retValue = NO;
if( self.viewCount == kOperateOnCount - 1 )
{
retValue = YES;
self.viewCount = 0;
}
else
{
self.viewCount++;
}
return retValue;
}
#end
#implementation CountedViewController
-(void)viewDidLoad:(BOOL)animated
{
[super viewDidLoad:animated];
BOOL shouldPerform = [[ViewCountManager viewCountManager] shouldPerformOperation];
[self performOperation];
}
#end
I am using facebook SDK 3.0 in my app. The delegate method is called twice when after logging to facebook.
- (void)loginViewFetchedUserInfo:(FBLoginView *)loginView
user:(id<FBGraphUser>)user {
//loginThroughFb=TRUE;
NSString *userId=[[NSString alloc] initWithString:[user id]];
[self soapCallForLogin:#"" password:#"" deviceId:#"" fbid:userId];
NSLog(#"%#",userId);
[userId release];
}
I tried 'HelloFacebookSample' project and the method is called only once.
So I guess the best solution for such case is to keep a reference to the last user object and compare it to the new object you get the next call, and if they're equal you can just ignore that call.
- (void)loginViewFetchedUserInfo:(FBLoginView *)loginView user:(id<FBGraphUser>)user {
if (![self isUser:cachedUser equalToUser:user]) {
cachedUser = user;
/// Do something
}
}
- (BOOL)isUser:(id<FBGraphUser>)firstUser equalToUser:(id<FBGraphUser>)secondUser {
return
[firstUser.objectID isEqual:secondUser.objectID] &&
[firstUser.name isEqual:secondUser.name] &&
[firstUser.first_name isEqual:secondUser.first_name] &&
[firstUser.middle_name isEqual:secondUser.middle_name] &&
[firstUser.last_name isEqual:secondUser.last_name] &&
...
}
I also had this problem. I managed to fix it with an ugly hack, but it works. I keep a counter in the FBLoginView delegate. When the fetchedUserInfo is called, I check the counter. If it is greater than zero, return. Otherwise, do two things -
1. increment the message counter
2. Fire a delayed event that zeroes the message counter again.
So your fetchedUserInfo method will look like this:
- (void)loginViewFetchedUserInfo:(FBLoginView *)loginView
user:(id<FBGraphUser>)user {
if ([self messageCounter] >0)
return;
else
{
self.messageCounter++;
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 3 * NSEC_PER_SEC), dispatch_get_current_queue(), ^{
[self setMessageCounter:0];
});}
// Do whatever you were going to do }
Fixed in FB SDK 3.8 released on Sept 18 2013. The delegate methods are now called once per login regardless of how many times the repeated logging out and back in occur.
I was also able to reproduce this on FB SDK 3.7.1 and within their own sample program "Scrumptious"
As mentioned (at least for me) this only happens after:
Logging in once
Logging out
Logging back in (Now it happens)
What is interesting is the order of calls on re-logins:
On the first login I the calls I see are:
- (void)loginViewShowingLoggedInUser:(FBLoginView *)loginView;
- (void)loginViewFetchedUserInfo:(FBLoginView *)loginView user:(id<FBGraphUser>)user;
On the 2nd (and later) logins I see:
- (void)loginViewFetchedUserInfo:(FBLoginView *)loginView user:(id<FBGraphUser>)user;
- (void)loginViewShowingLoggedInUser:(FBLoginView *)loginView;
- (void)loginViewFetchedUserInfo:(FBLoginView *)loginView user:(id<FBGraphUser>)user;
Which gives a handy little workaround of setting a flag in the middle method like so:
- (void)loginViewShowingLoggedInUser:(FBLoginView *)loginView {
// Set flag
self.isFirstLoginDone = YES;
}
- (void)loginViewFetchedUserInfo:(FBLoginView *)loginView user:(id<FBGraphUser>)user {
// Check
if(self.isFirstLoginDone) {
// Execute code I want to run just once
NSLog(#"fetched");
}
// Don't forget to clear the flag (I guess it shouldn't matter if everything is cleaned up)
self.isFirstLoginDone = NO;
}
There could be another reason, which i jsut faced.
My situation:
ViewController A has a login (With fbloginview and its delegate set)
User chooses to register, moves to ViewController B with another fbloginview and its delegate set.
The above makes the delegate fire twice.
I have fixed this by setting delegate to nil on ViewWillDisappear in ViewController A.
-(void) viewWillAppear:(BOOL)animated{
[super viewWillAppear:animated];
fbLoginButton.delegate=self;
}
-(void)viewWillDisappear:(BOOL)animated{
[super viewWillDisappear:animated];
fbLoginButton.delegate=nil;
}
I used this simple trick :
(Define an int facebookCounter in your interface)
- (void)loginViewFetchedUserInfo:(FBLoginView *)loginView
user:(id<FBGraphUser>)user {
if (self.facebookCounter==0) {
self.facebookCounter++;
return;
}
//Do stuff here
}
I needed to add thread safety in this method. A simple class variable did not work. The following two options will work, depending on the use case-
- (void)loginViewFetchedUserInfo:(FBLoginView *)loginView user:(id<FBGraphUser>)user {
//self.executedOnce = NO; in the init method of this class
#synchronized(self){
if(!self.executedOnce) {
//do something once per init of this class
self.executedOnce = YES;
}
}
//OR- This will only execute once in the lifetime of the app, thus no need for the executedOnce flag
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
//do something once per lifetime of the app
});
}
just in the loginViewFetchedUserInfo method set the delegate of the loginView to nil. then it can never be called. and if you need the login again, set the delegate to the correct object.
I have an iPhone application in which I am testing in the applicationDidBecomeActive: that if the selected viewcontroller's rootview is there, then I want to call one webservice, otherwise not when I am coming from background to foreground I am taking the stack and checking it. But now even if I am in the rootview the webservice is not getting called. Can anybody help me on this?
Here is my code snippet:
- (void)applicationDidBecomeActive:(UIApplication *)application{
NSLog(#"applicationWilssnd");
if(tabBarController.selectedIndex==0)
{
NSArray *mycontrollers = self.tabBarController.viewControllers;
NSLog(#"%#",mycontrollers);
///if([mycontrollers objectAtIndex:0]!=)
///[[mycontrollers objectAtIndex:0] popToRootViewControllerAnimated:NO];
PinBoardViewController *pinvc=(PinBoardViewController*)[[mycontrollers objectAtIndex:0]topViewController] ;
if([mycontrollers objectAtIndex:0]!=pinvc)
{
}
else
{
[pinvc merchantnews];
}
mycontrollers = nil;
tabBarController.selectedIndex = 0;
}
}
`here the merchantnews is not getting called.
PinBoardViewController *pinvc=(PinBoardViewController*)[[mycontrollers objectAtIndex:0]topViewController] ;
if([mycontrollers objectAtIndex:0]!=pinvc)
Instead of this, try this
PinBoardViewController *pinvc=(PinBoardViewController*)[[mycontrollers objectAtIndex:0]topViewController] ;
if(pinvc isKindOfClass:[PinBoardViewController class]){
// Do ur stuff
}
I want to get a pointer reference to UIKeyboard *keyboard to the keyboard on screen so that I can add a transparent subview to it, covering it completely, to achieve the effect of disabling the UIKeyboard without hiding it.
In doing this, can I assume that there's only one UIKeyboard on the screen at a time? I.e., is it a singleton? Where's the method [UIKeyboard sharedInstance]. Brownie points if you implement that method via a category. Or, even more brownie points if you convince me why it's a bad idea to assume only one keyboard and give me a better solution.
Try this:
// my func
- (void) findKeyboard {
// Locate non-UIWindow.
UIWindow *keyboardWindow = nil;
for (UIWindow *testWindow in [[UIApplication sharedApplication] windows]) {
if (![[testWindow class] isEqual:[UIWindow class]]) {
keyboardWindow = testWindow;
break;
}
}
// Locate UIKeyboard.
UIView *foundKeyboard = nil;
for (UIView *possibleKeyboard in [keyboardWindow subviews]) {
// iOS 4 sticks the UIKeyboard inside a UIPeripheralHostView.
if ([[possibleKeyboard description] hasPrefix:#"<UIPeripheralHostView"]) {
possibleKeyboard = [[possibleKeyboard subviews] objectAtIndex:0];
}
if ([[possibleKeyboard description] hasPrefix:#"<UIKeyboard"]) {
foundKeyboard = possibleKeyboard;
break;
}
}
}
How about using -[UIApplication beginIgnoringInteractionEvents]?
Also, another trick to get the view containing the keyboard is to initialize a dummy view with CGRectZero and set it as the inputAccessoryView of your UITextField or UITextView. Then, get its superview. Still, such shenanigans is private/undocumented, but I've heard of apps doing that and getting accepted anyhow. I mean, how else would Instagram be able to make their comment keyboard interactive (dismiss on swipe) like the Messages keyboard?
I found that developerdoug's answer wasn't working on iOS 7, but by modifying things slightly I managed to get access to what I needed. Here's the code I used:
-(UIView*)findKeyboard
{
UIView *keyboard = nil;
for (UIWindow* window in [UIApplication sharedApplication].windows)
{
for (UIView *possibleKeyboard in window.subviews)
{
if ([[possibleKeyboard description] hasPrefix:#"<UIPeripheralHostView"])
{
keyboard = possibleKeyboard;
break;
}
}
}
return keyboard;
}
From what I could make out, in iOS 7 the keyboard is composed of a UIPeripheralHostView containing two subviews: a UIKBInputBackdropView (which provides the blur effect on whatever's underneath the keyboard) and a UIKeyboardAutomatic (which provides the character keys). Manipulating the UIPeripheralHostView seems to be equivalent to manipulating the entire keyboard.
Discaimer: I have no idea whether Apple will accept an app that uses this technique, nor whether it will still work in future SDKs.
Be aware, Apple has made it clear that applications which modify private view hierarchies without explicit approval beforehand will be rejected. Take a look in the Apple Developer Forums for various developers' experience on the issue.
If you're just trying to disable the keyboard (prevent it from receiving touches), you might try adding a transparent UIView that is the full size of the screen for the current orientation. If you add it as a subview of the main window, it might work. Apple hasn't made any public method of disabling the keyboard that I'm aware of - you might want to use one of your support incidents with Apple, maybe they will let you in on the solution.
For an app I am currently developing I am using a really quick and easy method:
Add this in the header file:
// Add in interface
UIWindow * _window;
// Add as property
#property (strong, nonatomic) IBOutlet UIView * _keyboard;
Then add this code in the bottom of the keyboardWillShow function:
-(void) keyboardWillShow: (NSNotification *) notification {
.... // other keyboard will show code //
_window = [UIApplication sharedApplication].windows.lastObject;
[NSTimer scheduledTimerWithTimeInterval:0.05
target:self
selector:#selector(allocateKeyboard)
userInfo:nil
repeats:NO];
}
This code look for when the keyboard is raised and then allocates the current window. I have then added a timer to allocate the keyboard as there were some issues when allocated immediately.
- (void)allocateKeyboard {
if (!_keyboard) {
if (_window.subviews.count) {
// The keyboard is always the 0th subview
_keyboard = _window.subviews[0];
}
}
}
We now have the keyboard allocated which gives you direct "access" to the keyboard as the question asks.
Hope this helps
Under iOS 8 it appears you have to jump down the chain more than in the past. The following works for me to get the keyboard, although with custom keyboards available and such I wouldn't rely on this working unless you're running in a controlled environment.
- (UIView *)findKeyboard {
for (UIWindow* window in [UIApplication sharedApplication].windows) {
UIView *inputSetContainer = [self viewWithPrefix:#"<UIInputSetContainerView" inView:window];
if (inputSetContainer) {
UIView *inputSetHost = [self viewWithPrefix:#"<UIInputSetHostView" inView:inputSetContainer];
if (inputSetHost) {
UIView *kbinputbackdrop = [self viewWithPrefix:#"<_UIKBCompatInput" inView:inputSetHost];
if (kbinputbackdrop) {
UIView *theKeyboard = [self viewWithPrefix:#"<UIKeyboard" inView:kbinputbackdrop];
return theKeyboard;
}
}
}
}
return nil;
}
- (UIView *)viewWithPrefix:(NSString *)prefix inView:(UIView *)view {
for (UIView *subview in view.subviews) {
if ([[subview description] hasPrefix:prefix]) {
return subview;
}
}
return nil;
}