I have an NSDocument application that restores its windows when it is reopened. I would like to check the number of windows and perform an action (show a welcome window) if there are none.
I tried to check NSDocumentController.shared().documents.count but it seems I check it at the wrong time because it is always 0 in the delegate lifecycle functions.
How can I perform an action when the application is launched without restoring any windows?
Here's what I do in my app: I just dispatch_after say, 0.5 seconds and then check the number of documents. That allows me enough time to restore at least one document if there are any to restore. This does result in a noticeable delay, of course, but I feel that it's short enough that most users won't realize it (especially if your app is able to load up quickly enough).
Related
I made an attendance app in Flutter in which I want to restrict employees to use only network provided time so that employees won't be able to temper the date and time.
Is there any option or solution to implement this in android and iOS as well?
Using this package datetime_settings we will get the settings of Automatic date & time of mobile so when automatic date & time is on mobile will give us an accurate network time otherwise we will show an error to turn on the automatic date & time in settings. That's how I used to restrict users to use only network-provided time.
I'll tell you what worked for me. Hope this can help you. I don't know if it's the most optimized way to do it, but it worked very well for me:
You need to create an internal clock for your app, and from this, use it instead of the DateTime.now() function. For this, you must take the server time when opening the app, and keep it updated with a timer that runs every 1 second.
Please note that the app goes to sleep (or closes) when the device is locked or the app is minimized for a certain amount of time (this depends on the operating system and battery saver settings), thereby stopping the internal clock, and consequently, it is delayed when the app is activated again. In my case, I got around this problem by using a foreground service that I designated to perform this task (I used flutter_foreground_task). Another advantage of using a foreground service, is that the user can close the app and the clock keeps running (and in my case, I also perform other simple tasks periodically).
If the user does not manipulate the system time, the difference should never reach 1 second.
Optionally, you could check when retrieving the server time, the difference with the device time, and if it is greater than a certain gap that you determine, warn the user, so that he can correct it if he prefers, so that he does not see a discrepancy with the time recorded and displayed by the application.
Regards.
I have a little issue with a form in a delphy XE2 application:
It's an old issue on this application and i have begin to work on it just since a little time.
When the user choose to launch the process with a button's event, my application launch a connexion with an OPCServer , an SQLServer and construct the form for a good following of data take on the tow servers.
The construction of my form involves a blockage of the interface (for approximately 15 sec) because of lot's of data which are necessary for make it.
When it freeze, if the user want drag the form, she go far away, and usually with the TMainMenu which go out of the screen. After that, it's impossible to use the application because we can't drag and we need to close and re-open.
In the old version, the form be already construct before the connexion. So the modification for a dynamic form isn't in link with this issue.
Life of my event :
-Open connexion with OPC Server
-Open SQL Connexion
-Send SQL Command Text
-FieldByName('') for update my UI (Button.Caption// TPage.TStaticText.Caption // TPage.Label1.Caption)
-FieldByName('') for update an array of record
-Close SQL Connexion
-Open SQL Connexion
-Send SQL CommandText
-FieldByName('') for update an other array of record
-Panel.Visible(false)
-TPage.Panel.Show;
-TPage.Panel.BringToFront;
So I haven't MainForm modification can change its position.
I'm a young developer, so I don't know why it moving and what I can make for repair that...
If you want a part of code, ask me what and i edit this, it's very long and i don't want spam answer.
Thank's for read.
The core of your problem is that you have a lengthy process (form construction) which completely blocks the main thread so your application isn't able to process normal Windows messages at the same time. That is why when you move your application it doesn't properly update its interface.
Now based on your description you already have this form construction process split into multiple steps so you could call Application.ProcessMessages between them.
This will force your application to update its UI part.
But beware calling Application.ProcessMessages often could hurt your application performance quite a bit. Why? It is usually a lengthy process because it forces your application to process all the messages that are in its queue.
Normally not all of these messages get processed as soon as they arrive. Windows groups them in the message queue by their priority list, making sure that high priority messages like WM_PAINT are processed as soon as possible while some other low priority messages like demand for application to respond to OS so that OS can see if the application is still working are mostly processed when application is idle or when they are in queue for certain amount of time.
So that is why Application.ProcessMessages can be so slow as it forces your application to process all messages regardless of their priority.
Also bear in mind that using Application.ProcessMessages can in certain scenarios actually become a bit dangerous.
Let me give you an example:
Lets say that clicking on a button starts a lengthy job which can take some time to finish. Now in order to allow your form to be updated you call Application.ProcessMessages in certain intervals. So far it is all good. But what happens if user clicks on that button again?
Since you are calling Application.ProcessMessages which forces your application to process all the messages and since clicking on button creates a MouseClick message which then fires buttons OnClick event which then executes the OnClick method that has been assigned to buttons OnClick event in the end this will cause the same method that was executed on first button click to be executed again.
So now you have this method partially done from first button click and same method executing again for second mouse click. Now the method that was executed from the second click will finish first and then the method that was started from first button click but was interrupted with Application.ProcessMessages handling the second button click will continue its execution to the end.
This all can lead to strange bugs which are hard to track, because you as a programmer normally don't predict that your end user might have clicked the button twice.
So to avoid this I strongly recommend you implement some safeguard mechanisms to prevent such scenarios by temporarily disabling a button for instance.
But the best solution is always to show your user that your application is working which in most cases will dissuade them from clicking the button again, but unfortunately not always.
You should also take a good care when dynamically constructing a form to enable the controls only after all of the controls have been successfully constructed. Failing to do so the user might click on one of your controls and that control could attempt to access some other control which hasn't yet been created at the time. The result hard to track bug which causes Access Violation.
You might also consider showing a splash screen at start instead of half built form. Why?
For once it is much nicer to see and it tells your users to wait a bit. And for second having main form hidden until it is fully created makes sure that user won't be doing any clicks on it prematurely.
When launching my app from a custom URL scheme, when app is not backgrounded, the launch sequence is taking longer then I would like. I want to use time profiler to see what methods are taking so long. I know on run there is an option for "Wait for App Launch" so I can launch it using the URL, but I don't see that under the profiling scheme. Does anyone know a way that I can launch the app fresh, using the URL, and have time profiler running on launch?
"see what methods are taking so long"
Do you suppose some method (or a few) are sopping up a lot of CPU time in themselves or by calling other methods that do?
If so, it will be easy to fix, but it's Not Likely.
More likely the time is spent in I/O of one sort or another, and you need to figure out why, not where.
If you're able to start it under a debugger (say by using #ChrisTruman's recommendation), then all you need to do is interrupt it with Ctrl-C, Ctrl-Break, Escape, or whatever key combination interrupts it.
Do this during the time when, subjectively, it is slow.
Let's suppose the startup is taking three times longer than you think it should.
If that's so, that means two thirds of the time is spent doing the unnecessary I/O or whatever it is.
That means each time you interrupt it, the probability is 2/3 that you will catch it in the act of doing whatever causes the slowness.
So interrupt it a few times, and each time just read the stack, look at variables, etc.
You will see why it's being slow.
Don't even look for where - that will appear by itself.
That's the basic idea behind this technique.
I'm currently working on a new game for iOS using Cocos2D. The game needs to advance states after x amount of time since the first launch. So for example:
State - Time
initial launch
24hrs
48hrs
My first idea was to just get the data and time on first launch and save it to a file. Then I could check it ever now and again to see how much time has passed. The problem with this is I need it to be in realtime so that the changes will take effect immediately once the state is reached. It also needs to continue when the user is not using the app. The functionality I'm looking for is kind of similar to how the iOS strategy games work where you build structures that take x amount of time.
Anyway my question(s) is; is there some sort of library that can accomplish this and how can I get it to continue after the user exits the app?
It can't. There is - apart from kind of misusing video/music playing etc. no way for your app to do work while it is not running.
You have two things you can do to simulate that behavior (and I suppose the strategy games do this, too):
You can calculate at any time while a user is still running your app the points in the future when something should happen (eg a housing structure is finished). When the user leave your app, store these future times as local events - then the user will get notified that something has happened in your game (eg message "The church has been built. Do you want to go to church now?)". Pressing yes will open your app, and you can do whatever is necessary to indeed build the church. So in fact you don't do it at the time when it occurred, but when the user opens your app the next time.
Like 1, but without notification. Just remember when the user leaves the app (eg in your settings, I would use a property list; set it when the app delegate gets the appWillResignActive event), and the next time he starts do whatever would have been done in the meantime - he won't be able to tell the difference :-).
It's all about make believe here :-).
We often cache image and data to improve our iPhone app's performance. But what strategy do you use to manage the cache data, such as delete or update it?
I saved the images to TMP folder, but don't know when should I trigger to "checking out of date cache data and delete it": when the iPhone apps starts, or quits, or in idle time?
You should delete the cache when the iPhone invokes your "didReceiveMemoryWarning" function.
When the application launches or quits, the user is usually expecting responsiveness. Choose a minimum amount of real time, like 24 hours, and a minimum amount of idle time, like a minute. If the user has been idle for a minute and it is more than 24 hours from the last cache purge, then clean the cache. If you are keeping track of how much data is cached, then you could factor that in as well. If it has been more than 24 hours and/or there is more than a megabyte in the cache.
If you are sure the application is being quit normally, as opposed to being quit to answer a call or launch another application, then that might also be a good time.
If your application does something that the user has to wait for anyway, but that would not be affected by purging the cache, then that might also be a good time. For example, fetching some data from a server.
Appreciate for your responses.
I agree that checking for delete the cache at the start or quit time will reduce the program's performance. Moreover, quit time is also used for saving the program's state.
The idea to check for idle time in 1 min is quite ok, but I have to build mechanism to check idle for every 15 s during the application time. I don't think it's easy and good for performance.
At last, I decide to perform "check and delete cache" after I retrieve new Items (data + image). I will check for items (data +image) that doesn't need to be displayed anymore and delete it. I think it makes sense that the feature who saves the cache, will deletes the cache also.
Certainly, I will do this in another thread to avoid frozen the interface.
Is this good? Pls give me your opinions.
I personally dosn't like if cache is cleaned when i open a application or idle longer then about 1 minute. The idea cleaning if age of the cache is about 24hours is good.
My personal recommandation is to build stack of cache files. And then checking for the cache file creation/modification time or last cache file access. So clean in background (don't let become your app feel slow cause you're doing such tasks when starting or stopping an app) maybe in a thread (does iphone sdk support that? dont know :)) and check for "is cache file older then 24hrs? if yes > recache or delete file