i have one application it has mapview .
problem is that i want to show map. means right now when all data loaded then it show mapview. i want to show mapview before it loaded . how can i do this ?
Edit:
for show map i use this [self performSelector:#selector(methoname) withObject:nil afterDelay:0.02];
but by this other problem generate .problem is ,it show me two times activity indicator. any other thing ,like performselector but without activity indicator.
i dont want to show this thing.
You want to look at multithreading.
Basically, you should be retrieving your data in a background thread. If you do what you're doing right now (loading everything in the main thread) the UI cannot be updated until everything is loaded.
So, do something like this:
-(void)viewDidLoad{
mapView.hidden = NO;
[self performSelectorInBackground:#selector(getExtraMapData)];
}
-(void)getExtraMapData{
NSAutoReleasePool *pool = [[NSAutoreleasePool alloc] init];
[self downloadMapData];
[map addTheDataIDownloaded];//I've never used the mapView,
// so I don't know it's methods.
[pool release];
}
-(void)downloadMapData{
NSURL *mapDataURL = [NSURL URLWithString:#"http://aURLWithInfoForMyMap.com"];
NSData *mapData = [NSData dataWithContentsOfURL:mapDataURL];
}
Related
Im developing an IOS 5 app which takes a feed from a url and displays the posts in a tableview. I have a View controller that loads the table cells with the posts in the feed. This all works perfectly.
However, i wanted to use the SVProgressHUD to show whilst the feed is being loaded in a separate thread.
So in my -(void)viewDidLoad method I have the following:
- (void)viewDidLoad
{
[super viewDidLoad];
[SVProgressHUD showInView:self.view status:#"loading.." networkIndicator:YES];
dispatch_async(kBgQueue, ^{NSData* data = [NSData dataWithContentsOfURL: latestFeedURL];
[self performSelectorOnMainThread:#selector(fetchedData:) withObject:data waitUntilDone:YES];});
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(foregroundRefresh:) name:UIApplicationWillEnterForegroundNotification object:nil];
self.pull = [[PullToRefreshView alloc] initWithScrollView:(UIScrollView *) self.feedTableView];
[self.pull setDelegate:self];
[self.feedTableView addSubview:self.pull];
self.title = #"Latest";
}
- (void)fetchedData:(NSData *)responseData {
//parse out the json data
NSError* error;
NSDictionary* json = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:&error];
NSMutableArray* latestFeed = [json objectForKey:#"posts"]; //2
self.feedUpLoads = latestFeed;
NSLog(#"objects: %#", latestFeed); //3
[self.feedTableView reloadData];
[SVProgressHUD dismiss];
}
This all works fine, im getting the data which is loaded in a background thread and my table is displaying the posts with all the detail required. The problem I have is that the SVProgressHUD is not showing at all. Even if I put the [SVProgressHUD showInView line in the fetchData method, it's still not showing. (by the way i know the SVProgressHUD code works because I can actually make it show forexample in the viewWillAppear method.
Im guessing that it's not working because at the point when I'm calling it the view does not yet fully exist? But if that's the case where should I call it so that it shows whilst the feed is being called and where should I remove it?
Any help appreciated! thanks in advance!!
For anyone else having a similar problem, this can also happen because you have a long loop or a piece of code that takes a long time to execute. If this happens, your progress bar wont be shown until after the loop, which kind of defeats the purpose.
To solve this issue you need to you this:
(void)performSelectorInBackground:(SEL)aSelector withObject:(id)arg
Basically your code would look something like this:
- (IBAction)submitPost:(id)sender {
//now we show the loading bar and submit the comment
[SVProgressHUD showWithStatus:#"Submitting post" maskType:SVProgressHUDMaskTypeGradient];
SEL aSelector = #selector(submitDataOfPost);
[self performSelectorInBackground:aSelector withObject:sender];
}
This will basically load the progress bar, and in a background thread, the method you want to execute will be called. This makes sure that the UI is updated (shows the progress hud) at the same time that your code is executed.
I'm having a problem displaying an image in an image view, which is generated from data.
My program works as follows:
The user selects a row from a UITableView.
Upon selection, a new view (Event Description) is generated and has 3 NSStrings and an NSData object passed to it.
This data is displayed in the view, however a thread is also spawned to convert the NSData into an image and display it as without that there is a slight delay in displaying the description view.
This code works fine on the simulator, however when I run it on my iPhone and select a row, the first selection works fine, then all corresponding selections have a noticeable delay in displaying the image..
Here is my code:
- (void)viewDidLoad {
[super viewDidLoad];
//Display the selected events data
name.text = eventName;
date.text = eventDate;
description.text = eventDescription;
//Set the title of the navigation bar
self.navigationItem.title = eventName;
/* Operation Queue init (autorelease) */
NSOperationQueue *queue = [NSOperationQueue new];
/* Create our NSInvocationOperation to call loadDataWithOperation, passing in nil */
NSInvocationOperation *operation = [[NSInvocationOperation alloc] initWithTarget:self
selector:#selector(loadDataWithOperation)
object:nil];
/* Add the operation to the queue */
[queue addOperation:operation];
[operation release];
}
//Threaded operation
- (void) loadDataWithOperation {
//Set the event image
UIImage *img = [UIImage imageWithData: eventImageURLData];
image.image = img;
}
Does anyone have any idea whats causing this?
Thanks,
Jack
Simulator doesn't have memory constraints so it rarely flags the low memory problem. As such you're leaking NSOperationQueues. I see that you've marked it as autorelease but see no autorelease message. You should probably fix that. In addition to this, you should be sending the image update code to the main thread.
Goal is to "launch a spinner graphic at start of viewWillAppear that loads data before showing the tableview" so the user doesn't wonder why there's a delay before seeing the table. I.e. a UIActivityIndicatorView has been added to the window, and I just want to set the alpha to hide/show it.
I get this strange error when starting a thread to make sure the "spinning gears" imageview (tag=333) gets shown, before moving on to load/calculate stuff in viewWillAppear.
I don't get it on every call to [appdel addGearz] and [appdel removeGearz], it happens for both these, and it's random. It can happen after 2 viewWillAppears, or after 15. If I comment out the line that sets the alpha, everything works.
A typical viewWillAppear looks something like this,
[super viewWillappear];
self.title=#"Products listing"; //and other simple things
[appdel addGearz];
[self getProducts];
[self getThumbnails];
[myTableView reloadData]; //in case view already loaded and coming back from subview and data changed
And here is the code that crashes if the lines with .alpha are not commented out
-(void)addGearz {
[NSThread detachNewThreadSelector:#selector(gearzOn) toTarget:self withObject:nil];
}
-(void)removeGearz {
[NSThread detachNewThreadSelector:#selector(gearzOff) toTarget:self withObject:nil];
}
- (void)gearzOn {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
[window viewWithTag:333].alpha=1.0;
//
// [[window viewWithTag:333] setNeedsDisplay];
[pool drain];
}
- (void) gearzOff {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
[window viewWithTag:333].alpha=0.0;
//
// [[window viewWithTag:333] setNeedsDisplay];
[pool drain];
}
I've used someone else's code, so... anything obvious you can see? Surely I must be able to change alpha of UIViews in a thread? Do I need to "embed" the alpha-change in some "stop enumerating while I change this"-code?
I made it not crash by moving that alpha-change-line to above the pool alloc or below the [pool drain], but then I get a lot of "autoreleased with no pool in place - just leaking"-messages.
Apparently, there's something I don't understand about this thread code.
You must not try to modify the UI on a separate thread. UI should only be manipulated on the main thread.
Instead of detaching a new thread, you should use performSelectorOnMainThread:withObject:waitUntilDone:. This will ensure that the method will be called on the proper thread.
In my iPhone app, I want to add activity indicator on top of a searchbar.
When it is searching it should display activity indicator.
I have added the activity indicator in XIB and created its outlet.
I am making it hide when the searching finishes, but Activity Indicator does not display.
Problem
I figured out that search function(say A)(where I animate the activity indicator) in turn calls another function(say B) so the main thread is being used in executing the function B. But for activity indicator to animate we require the main thread.
So I tried calling function B using performSelectorInBackGround:withObject method. Now when I click search the activity indicator is shown but the functionality of function B does not execute.
What can be a work-around for this?
There is not quite enough in your question to go on, but to start debugging, I would do the following.
Verify that the activity variably is really wired to the UIActivityIndicator you are creating in IB. (I would set a breakpoint on the setHidden: lines and make sure the variable is not null. Or throw an NSAssert(activity,#"Whoops! actity is null"); in there.)
If the variable is indeed set, I would start checking that it is in the right place in the view hierarchy. (I'd try doing a [self.view addSubview:activity] and see that it appears. You might have to replace it somewhere else.)
You might also want to try having it on by default in IB, until you have everything figured out.
Good Luck. Hope this helps.
Save yourself the hassle of creating a custom activity indicator and use the standard one that's available for you already - in the top bar. Also, IMO users tend to expect that one to spin when something is happening.
UIApplication* app = [UIApplication sharedApplication];
app.networkActivityIndicatorVisible = YES;
Obviously, set it to NO when your activity is over.
First of all, make sure you have #synthesize activity at the top of your .m file. Then in the viewDidLoad method, type activity.hidesWhenStopped = TRUE;. Next, in the method that is called when the search starts, type [activity startAnimating]; and [activity stopAnimating]; in the method when the searching stops.
try this:
set hidesWhenStopped = NO, so that is displayed all the time and then hide and show it manually. But the View should be set in IB to hidden first.
- (void)startActivityView {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc]init];
activity_view.hidden = NO;
[pool drain];
}
- (void)stopActivityView {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc]init];
activity_view.hidden = YES;
[pool drain];
}
- (void)doSomething {
[self performSelectorInBackground:#selector(startActivityView) withObject:nil];
// do some time consuming work
[self performSelectorInBackground:#selector(stopActivityView) withObject:nil];
}
Perhaps you have a view in front of your activity indicator? What if you always bring it to the front....
loadView = [[UIActivityIndicatorView alloc]
initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
loadView.frame = CGRectMake(0.0, 0.0, 40.0, 40.0);
loadView.center = window.center;
loadView.opaque = NO;
[window addSubview: loadView];
[window bringSubviewToFront:loadView];
[loadView startAnimating];
I suggest that you use DSActivityView for showing your activity indicator. The source code can be found at Dejal blog.
Showing, and hiding, the activity view is a simple line of code.
[DSActivityView activityViewForView:self.view];
start animating the activity indicator and with a delay of 0.1 or 0.2 just call the other method u want.... i tried and it is working for me....
I have got the solution and it is as follows.
I just wrote the below line in Search button click event.
[NSThread detachNewThreadSelector:#selector(threadStartAnimating:) toTarget:self withObject:nil];
And defined the function threadStartAnimating: as follows:
-(void)threadStartAnimating:(id)data
{
[activityIndicator setHidden:NO];
[activityIndicator startAnimating];
}
I am totally stumped, here's the situation:
My app uses the Core Location framework to get the current location of the user and then pings my server at TrailBehind for interesting places nearby and displays them as a list. No problems.
To conserve batteries, I turn off the GPS service after I get my data from the server. If the user moves around while using the app and wants a new list he clicks "Refresh" on the navigation controller and the CLLocation service is again activated, a new batch of data is retrieved from the server and the table is redrawn.
While the app is grabbing data from my server I load a loading screen with a spinning globe that says "Loading, please wait" and I hide the navigation bar so they don't hit "back".
So, the initial data grab from the server goes flawlessly.
The FIRST time I hit refresh all the code executes to get a new location, ping the server again for a new list of data and updates the cells. However, instead of loading the table view as it should it restores the navigation controller bar for the table view but still shows my loading view in the main window. This is only true on the device, everything works totally fine in the simulator.
The SECOND time I hit refresh the function works normally.
The THIRD time I hit refresh it fails as above.
The FOURTH time I hit refresh it works normally.
The FIFTH time I hit refresh it fails as above.
etc etc, even refreshes succeed and odd refreshes fail. I stepped over all my code line by line and everything seems to be executing normally. I actually continued stepping over the core instructions and after a huge amount of clicking "step over" I found that the table view DOES actually display on the screen at some point in CFRunLoopRunSpecific, but I then clicked "continue" and my loading view took over the screen.
I am absolutely baffled. Please help!! Many thanks in advance for your insight.
Video of the strange behavior:
Relevant Code:
RootViewControllerMethods (This is the base view for this TableView project)
- (void)viewDidLoad {
//Start the Current Location controller as soon as the program starts. The Controller calls delegate methods
//that will update the list and refresh
[MyCLController sharedInstance].delegate = self;
[[MyCLController sharedInstance].locationManager startUpdatingLocation];
lv = [[LoadingViewController alloc] initWithNibName:#"Loading" bundle:nil];
[self.navigationController pushViewController:lv animated:YES];
[super viewDidLoad];
}
- (void)updateClicked {
//When the location is successfully updated the UpdateCells method will stop the CL manager from updating, so when we want to update the location
//all we have to do is start it up again. I hope.
[[MyCLController sharedInstance].locationManager startUpdatingLocation];
[self.navigationController pushViewController:lv animated:YES];
//LV is a class object which is of type UIViewController and contains my spinning globe/loading view.
}
-(void)updateCells {
//When the Core Location controller has updated its location it calls this metod. The method sends a request for a JSON dictionary
//to trailbehind and stores the response in the class variable jsonArray. reloadData is then called which causes the table to
//re-initialize the table with the new data in jsonArray and display it on the screen.
[[MyCLController sharedInstance].locationManager stopUpdatingLocation];
if(self.navigationController.visibleViewController != self) {
self.urlString = [NSString stringWithFormat:#"http://www.trailbehind.com/iphone/nodes/%#/%#/2/10",self.lat,self.lon];
NSURL *jsonURL = [NSURL URLWithString:self.urlString];
NSString *jsonData = [[NSString alloc] initWithContentsOfURL:jsonURL];
NSLog(#"JsonData = %# \n", jsonURL);
self.jsonArray = [jsonData JSONValue];
[self.tableView reloadData];
[self.navigationController popToRootViewControllerAnimated:YES];
[jsonData release];
}
}
CLController Methods: Basically just sends all the data straight back to the RootViewController
// Called when the location is updated
- (void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
fromLocation:(CLLocation *)oldLocation
{
NSLog(#"New Location: %# \n", newLocation);
NSLog(#"Old Location: %# \n", oldLocation);
#synchronized(self) {
NSNumber *lat = [[[NSNumber alloc] init] autorelease];
NSNumber *lon = [[[NSNumber alloc] init] autorelease];
lat = [NSNumber numberWithFloat:newLocation.coordinate.latitude];
lon = [NSNumber numberWithFloat:newLocation.coordinate.longitude];
[self.delegate noteLat:lat];
[self.delegate noteLon:lon];
[self.delegate noteNewLocation:newLocation];
[self.delegate updateCells];
}
}
The first thought is that you may not want to send startUpdatingLocation to the CLLocationManager until after you've pushed your loading view. Often the first -locationManager:didUpdateToLocation:fromLocation: message will appear instantly with cached GPS data. This only matters if you're acting on every message and not filtering the GPS data as shown in your sample code here. However, this would not cause the situation you've described - it would cause the loading screen to get stuck.
I've experienced similarly weird behavior like this in a different situation where I was trying to pop to the root view controller when switching to a different tab and the call wasn't being made in the correct place. I believe the popToRootViewController was being called twice for me. My suspicion is that your loading view is either being pushed twice or popped twice.
I recommend implementing -viewWillAppear:, -viewDidAppear:, -viewWillDisappear: and -viewDidDisappear: with minimal logging in your LoadingViewController.
- (void)viewWillAppear:(BOOL)animated {
NSLog(#"[%# viewWillAppear:%d]", [self class], animated);
[super viewWillAppear:animated];
}
- (void)viewDidAppear:(BOOL)animated {
NSLog(#"[%# viewDidAppear:%d]", [self class], animated);
[super viewDidAppear:animated];
}
- (void)viewWillDisappear:(BOOL)animated {
NSLog(#"[%# viewWillDisappear:%d]", [self class], animated);
[super viewWillDisappear:animated];
}
- (void)viewDidDisappear:(BOOL)animated {
NSLog(#"[%# viewDidDisappear:%d]", [self class], animated);
[super viewDidDisappear:animated];
}
Then, run a test on your device to see if they are always being sent to your view controller and how often. You might add some logging to -updateClicked to reveal double-taps.
Another thought, while your #synchronized block is a good idea, it will only hold off other threads from executing those statements until the first thread exits the block. I suggest moving the -stopUpdatingLocation message to be the first statement inside that #synchronized block. That way, once you decide to act on some new GPS data you immediately tell CLLocationManager to stop sending new data.
Can you try and debug your application to see where the control goes when calling updateCells? Doesn't seem to be anything apparently wrong with the app.
Make sure that there are no memory warnings while you are in the LoadingViewController class. If there is a memory warning and your RootViewController's view is being released, then the viewDidLoad will be called again when you do a pop to RootViewController.
Keep breakpoints in viewDidLoad and updateCells. Are you sure you are not calling LoadingViewController anywhere else?
So, I never did get this to work. I observe this behavior on the device only every time I call popViewController programatically instead of allowing the default back button on the navigation controller to do the popping.
My workaround was to build a custom loading view, and flip the screen to that view every time there would be a delay due to accessing the internet. My method takes a boolean variable of yes or no - yes switches to the loading screen and no switches back to the normal view. Here's the code:
- (void)switchViewsToLoading:(BOOL)loading {
// Start the Animation Block
CGContextRef context = UIGraphicsGetCurrentContext();
[UIView beginAnimations:nil context:context];
[UIView setAnimationTransition: UIViewAnimationTransitionFlipFromLeft forView:self.tableView cache:YES];
[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
[UIView setAnimationDuration:.75];
// Animations
if(loading) {
if (lv == nil) { lv = [[LoadingViewController alloc] initWithNibName:#"Loading" bundle:nil]; }
[self.view addSubview:lv.view];
[self.view sendSubviewToBack:self.tableView];
self.title = #"TrailBehind";
}
else {
[lv.view removeFromSuperview];
}
// Commit Animation Block
[UIView commitAnimations];
//It looks kind of dumb to animate the nav bar buttons, so set those here
if(loading) {
self.navigationItem.rightBarButtonItem = nil;
self.navigationItem.leftBarButtonItem = nil;
self.title = #"TrailBehind";
}
else {
UIBarButtonItem *feedback = [[UIBarButtonItem alloc] initWithTitle:#"Feedback" style:UIBarButtonItemStylePlain target:self action:#selector(feedbackClicked)];
self.navigationItem.rightBarButtonItem = feedback;
UIBarButtonItem *update = [[UIBarButtonItem alloc] initWithTitle:#"Move Me" style:UIBarButtonItemStylePlain target:self action:#selector(updateClicked)];
self.navigationItem.leftBarButtonItem = update;
[feedback release];
[update release];
}
}
Looking at your original code, I suspect this block very much:
- (void)viewDidLoad {
...
lv = [[LoadingViewController alloc] initWithNibName:#"Loading" bundle:nil];
[self.navigationController pushViewController:lv animated:YES];
[super viewDidLoad];
}
viewDidLoad is called every time the NIB is loaded, which can happen multiple times, especially if you run low on memory (something that seems likely given your remark that it only happens on device). I recommend that you implement -didReciveMemoryWarning, and after calling super, at the very least print a log so you can see whether it's happening to you.
The thing that bothers me about the code above is that you're almost certainly leaking lv, meaning that there may be an increasing number of LoadingViewControllers running around. You say it's a class variable. Do you really mean it's an instance variable? ivars should always use accessors (self.lv or [self lv] rather than lv). Do not directly assign to them; you will almost always do it wrong (as you are likely dong here).
I came across this while searching for the exact same issue, so while I'm sure you've already solved your problem by now, I figured I'd post my solution in case someone else runs across it...
This error seems to be caused when you assign two IBActions to the same UIButton in interface builder. It turned out that the button I used to push the view controller onto the stack was assigned to two IBActions, and each one was pushing a different controller onto the navigationController's stack (although you'll only end up seeing one of them - perhaps the last one to be called). So anyway, pressing the back button on the topmost view doesn't really dismiss it (or maybe it's dismissing the 2nd, unseen controller), and you have to press twice to get back.
Anyway, check your buttons and be sure they're only assigned to a single IBAction. That fixed it for me.