my app has around 200 UITableView rows, when i use simulator on xcode to filter data through UISearchBar, it filters and shows result instantly however, when i run my app in my iphone (iphone4, iOS 5.1.1), it hangs for couple of seconds before showing any search result. I'm using this code to filter data...
- (void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText{
[self.filteredData removeAllObjects];
if ([searchText length] > 0) {
self.isSearching = YES;
for (AClass *filteredData in self.allData) {
NSRange titleResultRange = [filteredData.name rangeOfString:self.searchBar.text options:NSCaseInsensitiveSearch];
if (titleResultRange.location != NSNotFound) {
[self.filteredData addObject:filteredData];
}
}
}
else self.isSearching = NO;
[self.tableView reloadData];}
I believe my code is okay since it's working perfectly fine on the simulator, is there anything i need to do to make it work faster on iphone?
btw, my iPhone is working perfectly fine, i use other apps, they work fine for me..
The reason your device is taking longer than the simulator is due to the amount of memory available. As a general rule, don't use the performance of your app in the simulator to judge your app's performance.
If you are filtering a very large data set in the way you describe, I would suggest using dispatch queues to perform your search instead of doing it all in the main queue. You can read about them here: http://developer.apple.com/library/ios/#documentation/General/Conceptual/ConcurrencyProgrammingGuide/OperationQueues/OperationQueues.html
In case you don't want to read the entire documentation, here's an example of what this would look like with your code.
- (void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText{
[self.filteredData removeAllObjects];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
if ([searchText length] > 0) {
self.isSearching = YES;
for (AClass *filteredData in self.allData) {
NSRange titleResultRange = [filteredData.name rangeOfString:self.searchBar.text options:NSCaseInsensitiveSearch];
if (titleResultRange.location != NSNotFound) {
[self.filteredData addObject:filteredData];
}
}
}
else self.isSearching = NO;
dispatch_async(dispatch_get_main_queue(), ^{
[self.tableView reloadData];
});
});
}
Please note that the example I am giving you is not thread safe... you will need to make sure that only one search is being performed at any given time or this code will crash, since the same array will be referenced across multiple queues. If you need more assistance, leave a comment and I'll try to get to it.
Related
I have part of my app written in JS and running inside of a WebView. I'm using the UIWebView shouldStartLoadWithRequest method to capture http requests as a means of communicating between JS and obj-c. This works great until I attempt to load a Modal View Controller over my webview from inside the shouldStartLoadWithRequest method. Once this happens, shouldStartLoadWithRequest is no longer called. Sometimes I need to dismiss this modal view controller and go back to the webview and do some things and then re-present the modal controller. The modal controller comes up the first time just fine, then I dismiss it and attempt to present it again by navigating to a URL from javascript and it no longer will present itself. NSLogs inside shouldStartLoadWithRequest are never run.
In my javascript I do something like this:
window.location='myapp:whateverMethod';
objective c code looks like this:
- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType {
NSString *requestString = [[request URL] absoluteString];
NSLog(#"REQUEST URL: %#", requestString);
if([requestString hasPrefix:#"myapp:"]) {
NSArray *components = [requestString componentsSeparatedByString:#":"];
NSString *function = [components objectAtIndex:1];
if([self respondsToSelector:NSSelectorFromString(function)]) {
[self performSelector:NSSelectorFromString(function)];
}
return NO;
}
return YES;
}
-(void) whateverMethod {
NSLog(#"whateverMethod called!");
// This is a quick way to grab my view controller from the storyboard, so assume it exists
UIViewController *splash = [self.storyboard instantiateViewControllerWithIdentifier:#"splashViewController"];
[self presentModalViewController:splash animated:NO];
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 2 * NSEC_PER_SEC), dispatch_get_current_queue(), ^{
[self dismissModalViewController:splash animated:NO];
});
}
At this point my webview is still visible. I navigate from page to page in my webapp and all javascript works great in it but the "shouldStartLoadWithRequest" delegate method of the webview no longer is called. I cannot figure out why. Does anyone have any ideas?
I noticed that Cordova doesn't set the window.location property. Instead it has two options: it either creates an iframe and sets the src of the iframe to that url, or it creates an XMLHttpRequest object e.g. in the iOSExec() function:
if (bridgeMode) {
execXhr = execXhr || new XMLHttpRequest();
// Changeing this to a GET will make the XHR reach the URIProtocol on 4.2.
// For some reason it still doesn't work though...
execXhr.open('HEAD', "file:///!gap_exec", true);
execXhr.setRequestHeader('vc', cordova.iOSVCAddr);
if (shouldBundleCommandJson()) {
execXhr.setRequestHeader('cmds', nativecomm());
}
execXhr.send(null);
} else {
execIframe = execIframe || createExecIframe();
execIframe.src = "gap://ready";
}
That being said, it may be beneficial to use something like Cordova instead of trying to roll it yourself (even if it's just embedding their view controller), since they handle a lot of the headaches that come up with webview delegates.
I've just had the same problem, but related to using a href="#" anchor.
This Stack Overflow answer sorted it
There are more answers on that thread that deal with widow.location, so you may have luck with them.
Checked out Cordova and they have their own queuing system, not really a help. But...
Disobedient Media's answer gave me an idea. Instead of window.location, why not try window.location.hash.
Now some JS code for logging is:
function sendMsgToNative(msg)
{
window.location.hash = '~cmd~' + msg;
}
console.log = function (msg) { sendMsgToNative('log~js ' + msg); };
and the Objective-C code is:
NSString *req = [request.URL absoluteString];
NSArray *components = [req componentsSeparatedByString:#"~"];
// Check for your protocol
if ([components count] > 1 && [(NSString *)[components objectAtIndex:1] isEqualToString:#"cmd"])
{
// Look for specific actions
if ([(NSString *)[components objectAtIndex:2] isEqualToString:#"log"])
{
NSString *logStr = [(NSString *)[components objectAtIndex:3] stringByReplacingPercentEscapesUsingEncoding: NSUTF8StringEncoding];
LOGI("%#", logStr);
}
}
You get the full URL including 'http:...' so I chose tilde instead of colon, and incremented the indices.
Now you can log all willy-nilly and send whatever amount of commands you want and they will all get through :-)
I (embarrassingly) spent a couple of hours working on this today, and realised that in my viewDidDisappear: I was setting the UIWebViewDelegate to nil!
All I needed to do to fix was once the modal was dismissed, re-set the UIWebViewDelegate and everything worked again.
I am fairly new to iOS Development and I've always wondered if a user running my application on iOS 4 were to try and run this code:
//POST TWEET//
- (void)showTweetSheet
{
TWTweetComposeViewController *tweetSheet =
[[TWTweetComposeViewController alloc] init];
tweetSheet.completionHandler = ^(TWTweetComposeViewControllerResult result) {
switch(result) {
case TWTweetComposeViewControllerResultCancelled:
break;
case TWTweetComposeViewControllerResultDone:
break;
}
dispatch_async(dispatch_get_main_queue(), ^{
[self dismissViewControllerAnimated:YES completion:^{
NSLog(#"Tweet Sheet has been dismissed.");
}];
});
};
[tweetSheet setInitialText:#"Check out this cool picture I found on #Pickr_"];
// Add an URL to the Tweet. You can add multiple URLs.
if (![tweetSheet addURL:[NSURL URLWithString:ImageHost]]){
NSLog(#"Unable to add the URL!");
}
[self presentViewController:tweetSheet animated:YES completion:^{
NSLog(#"Tweet sheet has been presented.");
}];
}
What would happen? Would the application just terminate with an error or will the code just not run? And how do I properly implement features that are OS specific? Would I just use something like this:
NSString *DeviceVersion = [[UIDevice currentDevice] systemVersion];
int DeviceVersionInt = [DeviceVersion intValue];
if (DeviceVersionInt > 5)
{
//do something.
}
else
{
//don't do a thing.
}
It will crash on iOS 4 if you write iOS5 features without checking if they are available or not. Try to implement Twitter like this
Class twClass = NSClassFromString(#"TWTweetComposeViewController");
if (!twClass) // Framework not available, older iOS
{
//use iOS4 SDK to implement Twitter framework
}
else {
//use Apple provided default Twitter framework
}
Make sure you have added Twitter Framework with weak link.
Id imagine that it would work the same as with any other api. If you link against a function which is not in a previous version, the program will crash on an attempt to call the function. Therefore, version switches are used, as you demonstrated, to avoid crashes.
The app would crash. If you want to implement features based on iOS, you can use a variety of methods. See this question.
I'm using iCloud in my app to load text files. When loading text files, this method is called by iCloud when I call _UIDocument openWithCompletionHandler:^(BOOL success) etc:
-(BOOL)loadFromContents:(id)contents ofType:(NSString *)typeName error:(NSError **)outError {
NSLog(#"Library loadFromContents: state = %d", self.documentState);
if (!_books) {
_books = [[NSMutableArray alloc] init];
}
//if (self.documentState > 7) {
// NSLog(#"document is either savingError (4), EditingDisabled (8) or both (12)... will not load");
// return NO;
//}
self.books = [NSKeyedUnarchiver unarchiveObjectWithData:contents];
if ([_delegate respondsToSelector:#selector(libraryDocumentUpdated:)]) {
[_delegate libraryDocumentUpdated:self];
}
return YES;
}
Now the big problem is when documentState is 8 (UIDocumentStateEditingDisabled) or 12 (UIDocumentStateSavingError & UIDocumentStateEditingDisabled). This will usually lead to a crash of the app. I tried to return NO if the documentState is > 7, i.e. if it is either 8 or 12 but this results in not loading any contents at all.
I guess the problem is that the UIDocument won't load anything into self.books if it editing is disabled or if there was a saving error.
What would be a good practice to handle such errors? Also, why didn't Apple suggest in their sample code to check the documentState before loading data into UIDocument (iCloud Docs)? I guess that I'm doing something fundamentally wrong.
Do you have conflict management implemented ?
In those scenarios you should attempt a number of things then retry loading the file the first being to check if
[NSFileVersion unresolvedConflictVersionsOfItemAtURL:]
has any conflicts, resolve them, retry opening the file,
[NSFileManager evictUbiquitousItemAtURL:]
and
[NSFileManager startDownloadingUbiquitousItemAtURL:]
if still can not open it, retry again after it downloaded.
I want to check whether the UIALertView is present on the screen or not, though I have done it by using the following method:
-(BOOL) isAlertShowing
{
for (UIWindow* window in [UIApplication sharedApplication].windows) {
NSArray* subviews = window.subviews;
if ([subviews count] > 0)
if ([[subviews objectAtIndex:0] isKindOfClass:[UIAlertView class]])
return YES;
}
return NO;
}
but I came to know that it is undocumented one. So, please tell me authenticate way of doing it.
In an app I submitted (and is approved), I have used a similar approach (see iPhone: detecting if a UIAlert/UIActionSheet are open)...
I don't see why you think it's not a valid method - I'd try it.
I have a UIScrollView that has a set of images loaded side-by-side inside it. You can see an example of my app here: http://www.42restaurants.com. My problem comes in with memory usage. I want to lazy load the images as they are about to appear on the screen and unload images that aren't on screen. As you can see in the code I work out at a minimum which image I need to load and then assign the loading portion to an NSOperation and place it on an NSOperationQueue. Everything works great apart from a jerky scrolling experience.
I don't know if anyone has any ideas as to how I can make this even more optimized, so that the loading time of each image is minimized or so that the scrolling is less jerky.
- (void)scrollViewDidScroll:(UIScrollView *)scrollView{
[self manageThumbs];
}
- (void) manageThumbs{
int centerIndex = [self centerThumbIndex];
if(lastCenterIndex == centerIndex){
return;
}
if(centerIndex >= totalThumbs){
return;
}
NSRange unloadRange;
NSRange loadRange;
int totalChange = lastCenterIndex - centerIndex;
if(totalChange > 0){ //scrolling backwards
loadRange.length = fabsf(totalChange);
loadRange.location = centerIndex - 5;
unloadRange.length = fabsf(totalChange);
unloadRange.location = centerIndex + 6;
}else if(totalChange < 0){ //scrolling forwards
unloadRange.length = fabsf(totalChange);
unloadRange.location = centerIndex - 6;
loadRange.length = fabsf(totalChange);
loadRange.location = centerIndex + 5;
}
[self unloadImages:unloadRange];
[self loadImages:loadRange];
lastCenterIndex = centerIndex;
return;
}
- (void) unloadImages:(NSRange)range{
UIScrollView *scrollView = (UIScrollView *)[[self.view subviews] objectAtIndex:0];
for(int i = 0; i < range.length && range.location + i < [scrollView.subviews count]; i++){
UIView *subview = [scrollView.subviews objectAtIndex:(range.location + i)];
if(subview != nil && [subview isKindOfClass:[ThumbnailView class]]){
ThumbnailView *thumbView = (ThumbnailView *)subview;
if(thumbView.loaded){
UnloadImageOperation *unloadOperation = [[UnloadImageOperation alloc] initWithOperableImage:thumbView];
[queue addOperation:unloadOperation];
[unloadOperation release];
}
}
}
}
- (void) loadImages:(NSRange)range{
UIScrollView *scrollView = (UIScrollView *)[[self.view subviews] objectAtIndex:0];
for(int i = 0; i < range.length && range.location + i < [scrollView.subviews count]; i++){
UIView *subview = [scrollView.subviews objectAtIndex:(range.location + i)];
if(subview != nil && [subview isKindOfClass:[ThumbnailView class]]){
ThumbnailView *thumbView = (ThumbnailView *)subview;
if(!thumbView.loaded){
LoadImageOperation *loadOperation = [[LoadImageOperation alloc] initWithOperableImage:thumbView];
[queue addOperation:loadOperation];
[loadOperation release];
}
}
}
}
EDIT:
Thanks for the really great responses. Here is my NSOperation code and ThumbnailView code. I tried a couple of things over the weekend but I only managed to improve performance by suspending the operation queue during scrolling and resuming it when scrolling is finished.
Here are my code snippets:
//In the init method
queue = [[NSOperationQueue alloc] init];
[queue setMaxConcurrentOperationCount:4];
//In the thumbnail view the loadImage and unloadImage methods
- (void) loadImage{
if(!loaded){
NSString *filename = [NSString stringWithFormat:#"%03d-cover-front", recipe.identifier, recipe.identifier];
NSString *directory = [NSString stringWithFormat:#"RestaurantContent/%03d", recipe.identifier];
NSString *path = [[NSBundle mainBundle] pathForResource:filename ofType:#"png" inDirectory:directory];
UIImage *image = [UIImage imageWithContentsOfFile:path];
imageView = [[ImageView alloc] initWithImage:image andFrame:CGRectMake(0.0f, 0.0f, 176.0f, 262.0f)];
[self addSubview:imageView];
[self sendSubviewToBack:imageView];
[imageView release];
loaded = YES;
}
}
- (void) unloadImage{
if(loaded){
[imageView removeFromSuperview];
imageView = nil;
loaded = NO;
}
}
Then my load and unload operations:
- (id) initWithOperableImage:(id<OperableImage>) anOperableImage{
self = [super init];
if (self != nil) {
self.image = anOperableImage;
}
return self;
}
//This is the main method in the load image operation
- (void)main {
[image loadImage];
}
//This is the main method in the unload image operation
- (void)main {
[image unloadImage];
}
I'm a little puzzled by the "jerky" scrolling. Since NSOperationQueue runs operations on separate thread(s) I'd have expected at worst you might see empty UIImageViews showing up on the screen.
First and foremost I'd be looking for things that are impacting the processor significantly as NSOperation alone should not interfere with the main thread. Secondly I'd be looking for details surrounding the NSOperation setup and execution that might be causing locking and syncing issues which could interrupt the main thread and therefore impact scrolling.
A few items to consider:
Try loading your ThumbnailView's with a single image at the start and disabling the NSOperation queuing (just skip everything following the "if loaded" check. This will give you an immediate idea whether the NSOperation code is impacting performance.
Keep in mind that -scrollViewDidScroll: can occur many times during the course of a single scroll action. Depending on how for the scroll moves and how your -centerThumbIndex is implemented you might be attempting to queue the same actions multiple times. If you've accounted for this in your -initWithOperableImage or -loaded then its possible you code here is causing sync/lock issues (see 3 below). You should track whether an NSOperation has been initiated using an "atomic" property on the ThumbnailView instance. Prevent queuing another operation if that property is set and only unset that property (along with loaded) at the end of the NSOperation processes.
Since NSOperationQueue operates in its own thread(s) make sure that none of your code executing within the NSOperation is syncing or locking to the main thread. This would eliminate all of the advantages of using the NSOperationQueue.
Make sure your "unload" operation has a lower priority than your "load" operation, since the priority is the user experience first, memory conservation second.
Make sure you keep enough thumbnails for at least a page or two forward and back so that if NSOperationQueue falls behind, you have a high margin of error before blank thumbnails become visible.
Make sure your load operation is only loading a "pre-scaled" thumbnail and not loading a full size image and rescaling or processing. This would be a lot of extra overhead in the middle of a scrolling action. Go even further and make sure you've converted them to PNG16 without an alpha channel. This will give at least a (4:1) reduction in size with hopefully no detectable change in the visual image. Also consider using PVRTC format images which will take the size down even further (8:1 reduction). This will greatly reduced the time it takes to read the images from "disk".
I apologize if any of this doesn't make sense. I don't see any issues with the code you've posted and problems are more likely to be occurring in your NSOperation or ThumbnailView class implementations. Without reviewing that code, I may not be describing the conditions effectively.
I would recommend posting your NSOperation code for loading and unloading and at least enough of the ThumbnailView to understand how it interacts with the NSOperation instances.
Hope this helped to some degree,
Barney
One option, although less visually pleasing, is to only load images when the scrolling stops.
Set a flag to disable image loading in:
-scrollViewWillBeginDragging:
Re-enable loading images when the scrolling stops using the:
-scrollViewDidEndDragging:willDecelerate:
UIScrollViewDelegate method. When the willDecelerate: parameter is NO, the movement has stopped.
the problem is here:
UIImage *image = [UIImage imageWithContentsOfFile:path];
It seems that threaded or not when you load a file from disk (which maybe that happens on the main thread regardless, I'm not totally sure) everything stalls. You normally don't see this in other situations because you don't have such a large area moving if any at all.
While researching this problem, I found two more resources that may be of interest:
Check out the iPhone sample project "PageControl": http://developer.apple.com/iphone/library/samplecode/PageControl/index.html
It lazy loads view controllers in a UIScrollView.
and -
Check out the cocoa touch lib: http://github.com/facebook/three20 which has a 'TTPhotoViewController' class that lazy loads photos/thumbnails from web/disk.
Set shouldRasterize = YES for the sub content view adde to the scrollview. It is seen to remove the jerky behavior of custom created scroll view like a charm. :)
Also do some profiling using the instruments in the Xcode. Go through the tutorials created for profiling by Ray Wenderlich it helped me a lot.