Hi I'm using NSFileHandle's readInBackgroundAndNotify method to get notifications when a log file has been updated.
I have the following code:
- (void)startReading
{
NSString *logPath = [NSHomeDirectory() stringByAppendingPathComponent:#"Library/Logs/MyTestApp.log"];
NSFileHandle *fh = [NSFileHandle fileHandleForReadingAtPath:logPath];
NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];
[notificationCenter addObserver:self
selector:#selector(getData:)
name:NSFileHandleReadCompletionNotification
object:fh];
[fh readInBackgroundAndNotify];
}
- (void) getData: (NSNotification *)aNotification
{
NSLog(#"notification received");
}
However the selector is never called and the notification is not received.
Add an NSLog to startReading to make sure that's getting called.
Log fh. My guess is that it's nil (most probably because you haven't created MyTestApp.log yet).
Related
I have an instance in a view called "PayView" and at the meantime I am doing openURL to open a separate app and to pass some data to it. This second app process the information I send and gives the response back.
At Appdelegate.m I have this handleOpenUrl which receives the response sent by the second app. Once I receive the response back I would like to go back to my "PayView" and use the response received from the second app along with already existing values I have in the instance.
My problem is as soon as the response from the second app reaches the appdelegate and reached the section "return yes", my main app goes back to this "PayView" and does nothing.
So how do I use the response object I received from appdelegate at my PayView along with already existing instance values?
I thought about using a global variable to store the "payView" instance/object and initiate a new instance from appdelegate for "Payview" and use the global along with the response json from appdelegate. However, I found many forums advising against using global.
So, ignoring the global and crating a new instance for "payview" causes loss of all previously stored data.
I am not an experienced iOS programmer and just work momentarily on someone else code.So, hope I explained my issue/question.
It would be great if I could get some valuable inputs :)
My appdelegate.m look like this,
-(BOOL)application:(UIApplication *)application handleOpenURL:(NSURL *)url{
if (!url) {
return NO;
}
// Unencode the URL's query string
NSString *queryString = [[url query] stringByRemovingPercentEncoding];
// Extract the JSON string from the query string
queryString = [queryString stringByReplacingOccurrencesOfString:#"response=" withString:#""];
// Convert the JSON string to an NSData object for serialization
NSData *queryData = [queryString dataUsingEncoding:NSUTF8StringEncoding];
// Serialize the JSON data into a dictionary
NSDictionary* jsonObject = [NSJSONSerialization JSONObjectWithData:queryData options:0 error:nil];
NSString *response = [jsonObject objectForKey:#"Result"]; //Get the response
UIAlertView *alert1 = [[UIAlertView alloc] initWithTitle:#"Result" message:response delegate:nil cancelButtonTitle:#"OK" otherButtonTitles: nil];
[alert1 show];
//PayView *pdv = [[PayViewController alloc] init];
//[pdv UseTransactionResult:jsonObject] ;
return YES;
}
and this is how I am calling open url from PayView
[[UIApplication sharedApplication]openURL:[NSURL URLWithString:[NSString stringWithFormat:#"mysecondapp://v2/data/?request=%#",requestEncodedString]] options:#{} completionHandler:^(BOOL success) {
if (success)
{
NSLog(#"Opened url");
}
}];
Edit 1:
Hi #ekscrypto, thanks for your valuable input. It is really helpful. I just have one problem with this. It is working just fine when I do the following in my PayView
Receiver:
[[NSNotificationCenter defaultCenter] addObserverForName:#"ActionIsComplete" object:nil queue:nil usingBlock:^(NSNotification *note){
//Completed Action
NSString *response = [note.userInfo objectForKey:#"Result"]; //Get the response
NSLog(response);
[self dismissViewControllerAnimated:YES completion:nil];
}];
However, when I try to do the same in the following method I get error "unrecognized selector sent to instance"
Receiver:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(ReceiveActionIsComplete:) name:#"ActionIsComplete" object:nil];
-(void)ReceiveActionIsComplete:(NSNotification *) notification
{
NSDictionary *jsonObject = (NSDictionary *)notification.userinfo;
[[NSNotificationCenter defaultCenter] removeObserver:self name:#"ActionIsComplete" object:nil];
Status = [jsonObject objectForKey:#"Status"];
Result = [jsonObject objectForKey:#"Result"];
NSLog([NSString stringWithFormat:#"%#%#",#"Status is: ", Status]);
NSLog([NSString stringWithFormat:#"%#%#",#"Result is: ", Result]);
}
in both cases my sender at Appdelegate looks like this.
Sender:
[[NSNotificationCenter defaultCenter] postNotificationName:#"ActionIsComplete" object:nil userInfo:jsonObject];
FYI: I tried sending the object in object instead of userInfo as well.
So what I am doing wrong? could you please help me.
Conclusion:
Sender: (AppDelegate.m)
[[NSNotificationCenter defaultCenter] postNotificationName:#"ActionIsComplete" object:nil userInfo:jsonObject];
Receiver: (PayView.m)
under - (void)viewDidLoad
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(ReceiveActionIsComplete:) name:#"ActionIsComplete" object:nil];
and the function to receive the results
-(void)ReceiveActionIsComplete:(NSNotification *) notification
{
NSDictionary *jsonObject = (NSDictionary *)notification.userInfo;
[[NSNotificationCenter defaultCenter] removeObserver:self name:#"ActionIsComplete" object:nil];
Status = [jsonObject objectForKey:#"Status"];
Result = [jsonObject objectForKey:#"Result"];
NSLog([NSString stringWithFormat:#"%#%#",#"Status is: ", Status]);
NSLog([NSString stringWithFormat:#"%#%#",#"Result is: ", Result]);
}
You could register a NotificationCenter observer in your PayView, and post a notification from your AppDelegate when the response is received. Via the notification object you can forward any information you need.
Let's assume that you define a struct with the information you want to pass along:
struct PaymentConfirmation {
let amount: Float
let confirmationNumber: String
}
In your PayView:
class PayView: UIView {
...
static let paymentProcessedNotification = NSNotification.Name("PayView.paymentProcessed")
let paymentProcessedObserver: NSObjectProtocol?
override func viewDidLoad() {
super.viewDidLoad()
paymentProcessedObserver = NotificationCenter.default.addObserver(
forName: PayView.paymentProcessedNotification,
object: nil,
queue: .main) { [unowned self] (notification) in
guard let confirmation = notification.object as PaymentConfirmation else { return }
self.paymentProcessed(confirmation)
}
}
deinit {
NotificationCenter.default.removeObserver(paymentProcessedObserver)
}
func paymentProcessed(_ confirmation: PaymentConfirmation) {
// do stuff
}
Then in your AppDelegate:
func application(_ app: UIApplication, open url: URL, options: [UIApplicationOpenURLOptionsKey : Any]) -> Bool {
// do stuff required with the callback URL
let confirmation = PaymentConfirmation(
amount: 3.0,
confirmationNumber: "Pay830da08.8380zSomething")
NotificationCenter.default.post(
name: PayView.paymentProcessedNotification,
object: confirmation)
}
For more information, check out https://medium.com/ios-os-x-development/broadcasting-with-nsnotification-center-8bc0ccd2f5c3
I implemented MPMovieViewController in my app but it has a problem i.e.when i play video in player then first time it is failed to play but next time it will play successfully with the same URL. I am not able to understand this different behavior with the same URL. I copied code here which i used in my app.
NSURL *fileURL = [NSURL URLWithString:#"http://nordenmovil.com/urrea/InstalaciondelavaboURREAbaja.mp4"];
MPMoviePlayerViewController * controller = [[MPMoviePlayerViewController alloc]initWithContentURL:fileURL];
controller.moviePlayer.movieSourceType= MPMovieSourceTypeFile;
[controller.moviePlayer setControlStyle:MPMovieControlStyleDefault];
[controller.moviePlayer prepareToPlay];
[controller.moviePlayer play];
[self presentMoviePlayerViewControllerAnimated:controller];
I suggest to handle the error for see what happens with your URL video (this is a tip that I founded long time ago in this answer)
Add this for capture the end of play:
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(handleMPMoviePlayerPlaybackDidFinish:)
name:MPMoviePlayerPlaybackDidFinishNotification
object:nil];
and this for see what happens:
- (void)handleMPMoviePlayerPlaybackDidFinish:(NSNotification *)notification
{
NSDictionary *notificationUserInfo = [notification userInfo];
NSNumber *resultValue = [notificationUserInfo objectForKey:MPMoviePlayerPlaybackDidFinishReasonUserInfoKey];
MPMovieFinishReason reason = [resultValue intValue];
if (reason == MPMovieFinishReasonPlaybackError)
{
NSError *mediaPlayerError = [notificationUserInfo objectForKey:#"error"];
if (mediaPlayerError)
{
NSLog(#"playback failed with error description: %#", [mediaPlayerError localizedDescription]);
}
else
{
NSLog(#"playback failed without any given reason");
}
}
}
Don't forget to remove the notification handler:
[[NSNotificationCenter defaultCenter] removeObserver:self
name:MPMoviePlayerPlaybackDidFinishNotification
object:nil];
With this workaround you should know the error with your stream, I hope this helps!
This code will call the method "defaultsChanged", when some value in UserDefaults changed
NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
[center addObserver:self
selector:#selector(defaultsChanged:)
name:NSUserDefaultsDidChangeNotification
object:nil];
This Code will give me the VALUE that changed
- (void)defaultsChanged:(NSNotification *)notification {
// Get the user defaults
NSUserDefaults *defaults = (NSUserDefaults *)[notification object];
// Do something with it
NSLog(#"%#", [defaults objectForKey:#"nameOfThingIAmInterestedIn"]);
}
but how can I get the NAME of the key, that changed??
As others stated, there is no way to get the info about the changed key from the NSUserDefaultsDidChange Notification. But there is no need to duplicate any content and check for yourself, because there is Key Value Observing (KVO) which also works with the NSUserDefaults, if you need to specifically be notified of a certain property:
First, register for KVO instead of using the NotificationCenter:
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[defaults addObserver:self
forKeyPath:#"nameOfThingIAmInterestedIn"
options:NSKeyValueObservingOptionNew
context:NULL];
don't forget to remove the observation (e.g. in viewDidUnload or dealloc)
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[defaults removeObserver:self forKeyPath:#"nameOfThingIAmInterestedIn"];
and finally implement this method to receive KVO notifications
-(void)observeValueForKeyPath:(NSString *)keyPath
ofObject:(id)object
change:(NSDictionary *)change
context:(void *)context
{
NSLog(#"KVO: %# changed property %# to value %#", object, keyPath, change);
}
There is no data provided in the notification's userInfo dictionary, so it looks like you're out of luck unless you want to keep another copy of the data stored in NSUserDefaults elsewhere and perform a diff on the two dictionaries.
Use custom notifications to determine what exactly happened, e.g.:
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:self.event, #"eventObject", nil];
[[NSNotificationCenter defaultCenter] postNotificationName:#"newEventCreated" object:nil userInfo:options];
If it is not an option with userDefaults, then just read all user defaults everytime you get your NSUserDefaultsDidChangeNotification notification and compair it with previous ones.
just add [[NSNotificationCenter defaultCenter] removeObserver:self name:NSUserDefaultsDidChangeNotification object:nil];
to your appDidBecomeActive method and then add
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(settingsChangedListener) name:NSUserDefaultsDidChangeNotification object:nil];
to your applicationDidEnterBackground
then use KVO observer as shown above when in the foreground
You can use dictionaryRepresentation to obtain the entire copy of NSUserDefaults as NSDictionary. Then it's a matter of comparing previous values and new values.
NSUserDefaults is not KVO compliant, the fact that it may fire some KVO notifications should not be relied upon and is a subject to change apparently.
For example:
- (void)setupUserDefaults {
self.userDefaults = [NSUserDefaults standardUserDefaults];
[self.userDefaults registerDefaults:#{ /* ... */ }];
self.userDefaultsDictionaryRepresentation = [self.userDefaults dictionaryRepresentation];
[notificationCenter addObserver:self
selector:#selector(userDefaultsDidChange:)
name:NSUserDefaultsDidChangeNotification
object:self.userDefaults];
}
- (void)userDefaultsDidChange:(NSNotification *)note {
NSDictionary *oldValues = self.userDefaultsDictionaryRepresentation;
NSDictionary *newValues = [self.userDefaults dictionaryRepresentation];
NSArray *allKeys = #[ /* list keys that you use */ ];
for(NSString *key in allKeys) {
id oldValue = oldValues[key];
id newValue = newValues[key];
if(![oldValue isEqual:newValue]) {
[self notifyObserversForKeyChange:key oldValue:oldValue newValue:newValue];
}
}
self.userDefaultsDictionaryRepresentation = newValues;
}
So, I managed to get NSTask to read asynchronously from a program, but I did it inside the class of a UIView in my storyboard. (Not an Obj-C expert)
My ideia is: I read the text from the program place it on a UITextView and then when there's more repeat the process via NSNotificationCenter
So far this is my code:
LView.m:
- (void)viewDidLoad
{
[super viewDidLoad];
NSPipe *out_pipe = [NSPipe pipe];
sshoutput = [out_pipe fileHandleForReading];
[sshoutput readInBackgroundAndNotify];
utilT = [[NSTask alloc] init];
[utilT setLaunchPath:#"/usr/bin/utilfc9"];
[utilT setArguments:[NSArray arrayWithObjects: #"-p", #"-f", #"log.txt", nil]];
[utilT setStandardOutput: out_pipe];
[utilT setStandardError: out_pipe];
[utilT launch];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(readPipe:) name:NSFileHandleReadCompletionNotification object:nil];
}
-(void)readPipe: (NSNotification *)notification
{
NSData *data;
NSString *new_input;
if( [notification object] != sshoutput ) { return };
data = [[notification userInfo] objectForKey:NSFileHandleNotificationDataItem];
new_input = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
self.log.text = [self.wifilog.text stringByAppendingFormat: #"\n%#", new_input];
if( utilT ) {
[sshoutput readInBackgroundAndNotify];
}
}
LView.h:
#import <UIKit/UIKit.h>
#import "NSTask.h"
NSTask *sshT;
NSFileHandle *sshoutput;
So far it works great, I get the data live without any issues.
But, how can I place this NSTask in a more "global" place like AppDelegate's application didFinishLaunchingWithOptions and then process the data and update multiple views in another classes? I tried and of course I can stuff like log.text = new_input inside AppDelegate because it's from another class, and including it does not solve the problem.
As you might noticed, I'm not interested in sending this to the AppStore. It's an app for myself to use on a jailbroken iPhone.
Thank you.
Quick way to do it is
In all of the Views that you want to recieve this same notification add the following
ReceiverView
-(void) viewDidLoad
{
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(read:) name:#"ReadTest" object:nil];
}
//read function
-(void) read:(NSNotification*)notification
{ // Do something with the notification }
Now in LView.m
-(void)readPipe: (NSNotification *)notification
{
NSData *data;
NSString *new_input;
if( [notification object] != sshoutput ) { return };
data = [[notification userInfo] objectForKey:NSFileHandleNotificationDataItem];
new_input = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
self.log.text = [self.wifilog.text stringByAppendingFormat: #"\n%#", new_input];
if( utilT ) {
[sshoutput readInBackgroundAndNotify];
}
//Add the following
[[NSNotificationCenter defaultCenter] postNotificationName:#"ReadTest" object:notification]
}
Be carefull, new_input is allocated but not released => Memory Leak
I made a class that uses NSURLConnection and KVC to make objects from plists on a server. Instruments says I have a bunch of memory leaks coming from the function that handles the data returned from the server:
- (void)connectionDidFinishLoading:(NSURLConnection *)connection{
hasOutstandingCall = NO;
NSError* sError;
NSDictionary* tmpDict = [NSPropertyListSerialization propertyListWithData:receivedData
options:NSPropertyListImmutable
format:NULL error:&sError];
self.lastResponse = [ServerResponse new];
//NSLog(#"server responded: %#",tmpDict);
[lastResponse setValuesForKeysWithDictionary:tmpDict];
if(tmpDict.count == 0){
lastResponse.success = NO;
lastResponse.errorId = -1;
lastResponse.errorMessage = #"Couldn't understand server response";
[[NSNotificationCenter defaultCenter] postNotificationName:#"serverDidRespond" object:self];
[[NSNotificationCenter defaultCenter] postNotificationName:#"requestDidFail" object:self];
NSLog(#"failed to deserialize response");
NSString* serverMessage = [[NSString alloc] initWithData:receivedData encoding:NSUTF8StringEncoding];
NSLog(#"SERVER SAID: %#",serverMessage);
[serverMessage release];
[receivedData release];
return;
}
[[NSNotificationCenter defaultCenter] postNotificationName:#"serverDidRespond" object:self];
if(lastResponse.success){
if(lastResponse.resultQuery)
NSLog(#"%# response: query with %d rows",lastFName, lastResponse.resultQuery.count);
else if(lastResponse.resultObject)
NSLog(#"%# response: object",lastFName);
[[NSNotificationCenter defaultCenter] postNotificationName:#"requestDidSucceed" object:self];
}else{
NSLog(#"%# response: ERROR id: %d, message: %#",lastFName, lastResponse.errorId, lastResponse.errorMessage);
[[NSNotificationCenter defaultCenter] postNotificationName:#"requestDidFail" object:self];
}
[receivedData release];
}
Instruments says I am leaking a server response, and a bunch of other things that pass through this function. Does the "Responsable Frame" thing always refer to whatever originally created the leaked object no matter what? Should I just be looking for how this stuff gets leaked down the road or do I have a problem here in this function? From what I understand, tempDict, sError are autoreleased when they come back from serialization. I'm sending the supposedly leaked serverResponse into a synthesized setter that gets released in the dealloc method, so I don't see what the problem is. Anyone got some insight?
self.lastResponse = [ServerResponse new];
That is most likely a double retain, assuming that lastResponse is an #property declared as retain (or your setter retains).
When Instruments identifies a leak, it shows where the item was allocated, but that may not be the cause of the leak. The leak will always be an unbalanced retain, but only sometimes will that retain be on the same line of the allocation (as it was in this case, apparently).