I have to 20-25 download images of 50 Kb- 2 Mb each and show them in a tableview.
I used ASIHTTPRequest asyn request to this. I observed that after some time the app gets stuck. This should not happen because I am using a async call. I thought something is wrong with ASIHTTPRequest and I observed that The didFinished selector gets called in the main thread. The only thing which I do is
-(void)didFinishedDownloadingImage:(ASIHTTPRequest*)request
{
NSData *responseData = [request responseData];
UIImage *image = [UIImage imageWithData:responseData];
[[data objectAtIndex:request.tag] setImage:image];
[self.tableView reloadData];
}
I don't think this should cause any problem. Also in cellforrowatindexpath I just do
- (UItableViewCell *)tableviewView:(UItableView *)tableview
cellForItemAtIndexPath:(NSIndexPath *)indexPath {
UserProfile * user = [data objecAtIndex:indexpath.row];
UITableViewCell *cell = [tableView
dequeueReusableCellWithReuseIdentifier:#"ProfileCell"
forIndexPath:indexPath];
if(cell == nil){
cell = [[UITableViewCell alloc] initWithStyle:UITableViewDefaultStyle];
}
NSString *fullname = [NSString stringWithFormat:#"%#\n%#",
user.firstname, user.lastname];
if(user.image != nil)
[cell.imageView setImage:user.image];
else{
[cell.imageView setImage:[UIImage imageNamed:#"placeholder.jpg"]];
}
[cell.label setText:fullname];
return cell;
}
But the app is slow and freezes for 1-2 sec which is a considerable amount of time.
I have seen apps which does this very smoothly. I tried using an image of fixed size 5Kb which has a very significance performance improvement with using the above code. I don't know why should that make a difference for big images in this case because all downloading is happening in other thread via ASIHTTP .
Please, replace your framework with AFNetworking.
You can simple use..
IImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 100.0f, 100.0f)];
[imageView setImageWithURL:[NSURL URLWithString:#"http://i.imgur.com/r4uwx.jpg"] placeholderImage:[UIImage imageNamed:#"placeholder-avatar"]];
or... directly in TableViewCell
NSURL *url = [[NSURL alloc] initWithString:[movie objectForKey:#"artworkUrl100"]];
[cell.imageView setImageWithURL:url placeholderImage:[UIImage imageNamed:#"placeholder"]];
"In the second line, we tell the image view where the thumbnail is located by passing an NSURL and we pass in a placeholder image, which is shown as long as our request has not returned a response"
Thats all!
Here you have an tutorial about that http://mobile.tutsplus.com/tutorials/iphone/ios-sdk_afnetworking/
It's easy to make assumptions about the root cause of a laggy/slow application. Instead of guessing, why don't you test your suspicions? Profile your application with the Time Profiler instrument. It'll tell you which methods and functions your application is spending the most time in.
Here are some ideas until you have a chance to profile:
You might consider downloading the full-res images and creating thumbnails in the background and then caching them in an NSCache object. You can also run [UIImage imageWithData:responseData]; in a background thread. It's thread-safe until the point at which it interacts with the view hierarchy.
Selectively reloading a single cell should be faster than reloading the entire tableview, especially one with lots of images. Furthermore if you're doing all of the networking and processing on a background queue, there's no reason scrolling the tableview should be slow. Can you show us your entire implementation of the -cellForRowAtIndexPath: method? You've mentioned that you think setImage: is your slow point because rendering is slow. If you reload a single cell, only one cell needs to be rendered. If you reload the entire tableview, every cell must be re-rendered.
Related
I have a UITableView that populates its cells with thumbnail images. In my case, the thumbnails are downloaded from a server. My code is as follows:
if (![self thumbnailExists])
{
self.thumbnailImageView.image = nil;
[self.activityIndicatorView startAnimating];
NSBlockOperation *operation = [NSBlockOperation blockOperationWithBlock:
^{
NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:self.thumbnailURL]];
UIImage *image = [UIImage imageWithData:data];
[[NSOperationQueue mainQueue] addOperationWithBlock:
^{
SubmenuScrollViewTableViewCell *submenuScrollViewTableViewCell = (SubmenuScrollViewTableViewCell*)[(UITableView*)self.superview cellForRowAtIndexPath:self.indexPath];
[submenuScrollViewTableViewCell.activityIndicatorView stopAnimating];
submenuScrollViewTableViewCell.thumbnailImageView.image = image;
}];
}];
[self.operationQueue addOperation:operation];
[self.operationQueues setObject:operation forKey:[self title]];
}
This code is based on the great WWDC2012 presentation: "Building Concurrent User Interfaces on iOS". The main difference between my code and the code in the presentation is I'm populating my cells with data that is retrieved from the web.
It works well for the most part, but the problem I'm having is if I scroll really fast, then one of the cells might show up with the wrong thumbnail (usually I noticed said cell would be a multiple of the cell from which the thumbnail belongs to). I should mention this code is being executed in the layoutSubviews method of an overridden UITableViewCell.
Can anyone spot any flaws in this code?
The reason your code is breaking is because of this line of code:
SubmenuScrollViewTableViewCell *submenuScrollViewTableViewCell = (SubmenuScrollViewTableViewCell*)[(UITableView*)self.superview cellForRowAtIndexPath:self.indexPath];
You are grabbing the cell at the index path when this is called and placing it in whatever cell is at this index path when the cell is reused. This puts a different image in a different cell when the view moves very fast and perhaps the response from the server comes in at a different time.
Make sure you cancel the operation in prepareForReuse and clear out the cell image so that it does not place the image in the wrong cell, or an image does not get re-used.
Also, it is generally bad practice to call the tableView from the cell itself.
The issue had to do with the fact that the above code was in the layoutSubviews method of a subclassed UITableViewCell I created. When I moved it back in the cellForRowAtIndexPath method, the problem was eliminated.
I am loading an image to a table view cell, each cell has an image. I've adapter a couple tutorials to the code below, but I am still having slow down.
I am loading these images from the documents directory. Any tips or ideas on how to speed this process up?
Edit Revised Code:
Beer *beer = (Beer *) [self.fetchedResultsController objectAtIndexPath:indexPath];
cell.displayBeerName.text = beer.name;
// did we already cache a copy of the image?
if (beer.image != nil) {
// good. use it. this will run quick and this will run most of the time
cell.beerImage.image = beer.image;
} else {
// it must be the first time we've scrolled by this beer. do the expensive
// image init off the main thread
cell.beerImage.image = nil; // set a default value here. nil is good enough for now
[self loadImageForBeer:beer atIndexPath:indexPath];
}
- (void)loadImageForBeer:(Beer *)beer atIndexPath:(NSIndexPath *)indexPath {
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
dispatch_async(queue, ^{
UIImage *image = [UIImage imageWithContentsOfFile:beer.imagePath];
beer.image = image;
dispatch_sync(dispatch_get_main_queue(), ^{
UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:indexPath];
cell.beerImage.image = image;
});
});
}
Your algorithm looks pretty good. You've avoided many of the typical pitfalls. If you're still having UI performance problems, I'd suggest a couple of things:
You should try caching your images in memory. You could use NSMutableArray or NSMutableDictionary, but at Best way to cache images on ios app? Caleb discusses the merits of the NSCache class, which simplifies the process. If you do cache images, make sure you respond to memory pressure and purge the cache if necessary. You can respond to didReceiveMemoryWarning or add yourself as an observer to the notification center's UIApplicationDidReceiveMemoryWarningNotification.
Make sure your cached images are thumbnail sized or else you'll always have a little stuttering in your UI (if you need a resizing algorithm, let us know) and it will use up memory unnecessarily;
When you dispatch your image update back to the main queue, you should do so asynchronously (why have that background queue hang around and tie up resources as it waits for the the block to be sent back to the main queue to finish ... this is especially an issue once you have a couple of images backed up during a fast scroll); and
When you dispatch back to the main queue, you should check to make sure cell you get from cellForRowAtIndexPath is not nil (because if cell loading logic gets too backed up (esp on slower devices), you could theoretically have the cell in question having scrolled off the screen and your algorithm could crash).
I use an algorithm very much like yours, with almost the same GCD structure (with the above caveats) and it's pretty smooth scrolling, even on older devices. If you want me to post code, I'm happy to.
If you're still having troubles, the CPU profiler is pretty great for identifying the bottlenecks and letting you know where you should focus your attention. There are some great WWDC sessions available online which focus on how to use Instruments to identify performance bottlenecks, and I found them to be very helpful to gain proficiency with Instruments.
Here is my code. In viewDidLoad, I initialize my image cache:
- (void)initializeCache
{
self.imageCache = [[NSCache alloc] init];
self.imageCache.name = #"Custom Image Cache";
self.imageCache.countLimit = 50;
}
And then I use this in my tableView:cellForRowAtIndexPath:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"ilvcCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
// set the various cell properties
// now update the cell image
NSString *imagename = [self imageFilename:indexPath]; // the name of the image being retrieved
UIImage *image = [self.imageCache objectForKey:imagename];
if (image)
{
// if we have an cachedImage sitting in memory already, then use it
cell.imageView.image = image;
}
else
{
cell.imageView.image = [UIView imageNamed:#"blank_image.png"];
// the get the image in the background
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// get the UIImage
UIImage *image = [self getImage:imagename];
// if we found it, then update UI
if (image)
{
dispatch_async(dispatch_get_main_queue(), ^{
// if the cell is visible, then set the image
UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:indexPath];
if (cell)
cell.imageView.image = image;
[self.imageCache setObject:image forKey:imagename];
});
}
});
}
return cell;
}
and
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
[self.imageCache removeAllObjects];
}
As an aside, one further optimization that you might contemplate would be to preload your cached images in a separate queue, rather than loading images in a separate thread just-in-time. I don't think it's necessary, as this seems to be more than fast enough for me, but it's one more option to speed up the UI.
Not much you can do here for the initial load, you're about as fast as it gets.
If it's still too slow, try loading smaller images if you can.
A couple of things:
First, be careful with -imageWithContentsOfFile, it won't cache anything. You're taking the full hit every time you load the image, as opposed to -imageNamed that'll keep the image warm in some cache.
You can of course cache that in your domain object, but I'd personally strongly advice against that.
Your memory footprint is going to go through the roof, forcing you to implement your own cache expiration mechanism, while Apple has a very good image cache through -imageNamed.
I'd be surprised if you can do a better job than apple on all 3 family of devices :)
Then, you're breaking the flyweight pattern of the UITableView here:
dispatch_sync(dispatch_get_main_queue(), ^{
cell.beerImage.image = image;
beer.image = image;
[cell setNeedsLayout];
});
Ask the table view to give your the cell at a given index rather than capture the cell in the block: by the time the image is loaded, that cell instance might actually have been reused for another index path, and you'll be displaying the image in the wrong cell.
And no need for -setNeedsLayout here, just changing the image is enough.
Edit: whoops! I missed the obvious thing with images in table view. What size are your images, what size is the image view, and what is the content mode on the image?
If your images are of a very different size than the image view and you're asking the imageview to resize, this will happen on the main thread and you'll take a massive performance hit there.
Resize the image to the image view off thread, after loading (a quick google search will give you the core graphics code to do that).
The missing step is to update the model with the fetched image. As it is, you're doing a new load for every cell every time. The model is the right place to cache the result of the relatively expensive load. Can you add a Beer.image property?
Then, your config code would look like this:
Beer *beer = (Beer *) [self.fetchedResultsController objectAtIndexPath:indexPath];
cell.displayBeerName.text = beer.name;
// did we already cache a copy of the image?
if (beer.image != nil) {
// good. use it. this will run quick and this will run most of the time
cell.beerImage.image = beer.image;
} else {
// it must be the first time we've scrolled by this beer. do the expensive
// image init off the main thread
cell.beerImage.image = nil; // set a default value here. nil is good enough for now
[self loadImageForBeer:beer atIndexPath:indexPath];
}
Moved the loader logic here for clarity ...
- (void)loadImageForBeer:(Beer *)beer atIndexPath:(NSIndexPath *)indexPath {
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
dispatch_async(queue, ^{
UIImage *image = [UIImage imageWithContentsOfFile:beer.imagePath];
beer.image = image;
dispatch_sync(dispatch_get_main_queue(), ^{
UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:indexPath];
cell.beerImage.image = image;
});
});
}
You can have a look on this question ,previously answered at stack overflow.
UIImage in uitableViewcell slowdowns scrolling table
or else try this code
- (void)configureCell:(BeerCell *)cell
atIndexPath:(NSIndexPath *)indexPath
{
Beer *beer = (Beer *) [self.fetchedResultsController objectAtIndexPath:indexPath];
cell.displayBeerName.text = beer.name;
UIImage *image = [UIImage imageWithContentsOfFile:beer.imagePath];
cell.beerImage.image = image;
[cell setNeedsLayout];
}
I am trying to loading images in tableViewCell asynchronously.
When I move the table up and down then images appear otherwise not.
AsyncImageView contains NSUrlConnection. It doesn't go inside the delegate "connectionDidFinishLoading". but when I move the table up or down then it goes inside this delegate function
Below is the code
CGRect frame;
frame.size.width=115; frame.size.height=100;
frame.origin.x=0; frame.origin.y=0;
AsyncImageView* asyncImage = [[[AsyncImageView alloc]
initWithFrame:frame] autorelease];
loadingTable=[[UIActivityIndicatorView alloc] initWithFrame:frame];
[cell.contentView addSubview:loadingTable];
[loadingTable startAnimating];
asyncImage.tag = 999;
NSURL* url = [NSURL URLWithString:[[videoCollection objectAtIndex:indexPath.row] videoImageUrl] ];
[asyncImage loadImageFromURL:url activity:loadingTable];
[cell.contentView addSubview:asyncImage];
First load all images and add them some data structure like array and after that show it to the table. Don't overlap your UI with network calls.
I'm sure as you know, all UI related business must be done on the main thread. However, downloading big amounts of data can and should be done in the background. And this tutorial with Grand Central Dispatch may be just what you need.
Download the images in a background thread and when its complete, let the main thread know of this and do the updating of the UI on the main thread.
I've done this yesterday.
The best way is to call the download in background and in the - (UITableViewCell *)cellForRowAtIndexPath:(NSIndexPath *)indexPath method.
This method will load the cell's image when the user would want to see it.
But warning ! To prevent downloading many time the same image, you should use a data structure (like dictionary) to check if the image has been downloaded.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
...
if([myPictures objectForKey:indexPath.row] == nil) {
[self performSelectorInBackground:#selector(downloadPhotoInBackground:) withObject:indexPath];
}
return cell
}
and in downloadPhotoInBackground:, don't forget to add your downloaded image to "myPictures" property.
I wonder if anyone can speculate or better yet provide a piece of code as for the implementation of the lengthy friends list in the Facebook iPhone app.
when you open the app and go strait to the friends list, you get the list almost in an instant, at least for me with ~500 friends.
when I try it in my own app it takes lots of precious seconds to populate the table view with the same data, so how does Facebook accomplished such a quick response time ?
upon looking at the tableview in the facebook app you notice there is no scroll bar usually found in such tableview, could that be one sign of the neat trick facebook is utilizing to achieve this rapid rows insert ? could it be they implemented some sort of a virtual tableview with only holds a few dozen rows but rotates them ?
any thoughts ?
the UITableView will let you do this. There are a number of examples on the internet with UITableView and Custom Cell's
Essentially, you load your images in the background, and you reuse the Cells that are in the tableview
EDIT Added example code to demonstrate how this is accomplished.
IMPORTANT NOTE
This code was not tested and may or may not actually function as is.
It was pasted with some editing for length. I did a lot more then this in my app, but in the interest of keeping with the example requested I omitted a lot.
On with the example:
Here is where I get the cell, load it with the items that are readily available. And send it to the background thread to load the rest.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"OfferCell";
static NSString *CellNib = #"OfferItem";
OfferCell* cell = (OfferCell*)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil)
{
NSArray *nib = [[NSBundle mainBundle] loadNibNamed:CellNib owner:self options:nil];
cell = (OfferCell*)[nib objectAtIndex:0];
}
NSDictionary* couponPackage = [self.jsonOfferData valueForKey:#"result"];
NSArray *couponList = [couponPackage valueForKey:#"offers"];
if ([couponList count] >= indexPath.row )
{
NSDictionary* couponData = [couponList objectAtIndex:indexPath.row];
Coupon *coupon = [[Coupon alloc] initWithDictionary:couponData];
NSDictionary *params = [NSDictionary dictionaryWithObjectsAndKeys:cell,#"cell",coupon,#"coupon", nil];
//Right here you would try to load any cached imaged from disk.
//Then send a Thread to the background to load the image.
[self performSelectorInBackground:#selector(loadTableViewCellData:) withObject:params];
//Load up the rest of the custom info into the custom cell.
[cell.captionLabel setText:coupon.name];
[cell.subTextLabel setText:coupon.subText];
[cell setAccessoryType:UITableViewCellAccessoryDetailDisclosureButton];
[cell setCommand:coupon.command];
[cell setParameter:coupon.commandArgs];
[cell setImageURL:coupon.imageURL];
[cell setImageAltURL:coupon.imageAltURL];
[cell setRegistrationCode:coupon.registrationCode];
[coupon release];
}
return cell;
}
as you can see, i call a background thread before i even load the custom content in the cell.
- (void) loadTableViewCellData:(NSDictionary*) objectData
{
OfferCell *cell = [objectData objectForKey:#"cell"];
Coupon *coupon = [objectData objectForKey:#"coupon"];
UIImage *image = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[coupon iconURL]]]];
[objectData setValue:image forKey:#"image"];
self performSelectorOnMainThread:#selector(setImageOnMainThread:) withObject:objectData
}
after downloading the image, i send a Main thread request to update the Image that is in the cell object.
- (void) setImageOnMainThread:(NSDictionary*) objectData
{
OfferCell *cell = [objectData objectForKey:#"cell"];
Coupon *coupon = [objectData objectForKey:#"coupon"];
UIImage *image = [objectData objectForKey:#"image"];
cell.icon.image = image;
}
##AGAIN This May not Actually Function. ##
I did not copy all of my code for this. this is a hammer out so you can get the idea.
play with the code and test it. but the fundamentals are.
Dequeue the cell that will fit your needs (Reuse Identifier)
Use the cell if it can be dequeue'd or create a new one with a reuse identifier (my example uses a xib file named OfferItem.xib)
Send a thread to the background that will load the image data from disk or url (a combination of both is recommended)
Send a thread back to the UI when you are ready to load the image into the View (Updating the UI must be done on the main thread)
if you can do that, then your friends list (or in this case offers) will be loaded up as fast as possible. and the Images will pop on the screen as soon as they download.
Also if you use a Caching technique it will be faster for subsequent loads because in the the first method {tableView:cellForRowAtIndexPath:} you would load up the cached image immediately.
Aside from that, this should load your cell's pretty fast.
They obviously load the data from a local resource (plist, ManagedObject, ...)
Have a look at some sample code to draw a TableView:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *kCellIdentifier = #"MyCellIdentifier";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:kCellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:kCellIdentifier] autorelease];
}
return cell;
}
The dequeueReusableCellWithIdentifier: thing is one reason why TableViews in iOS can draw quickly. It works somehow like this:
1)You provide an identifier for a cell you're creating.
2)Cells that are visible at first get alloced (with identifier)
3)When a Cell is moved off the screen it gets put on a pile MyCellIdentifier
4)Whenever the system needs to draw a cell of identifier:MyCellIdentifier it first looks whether there are any cells currently unused on the MyCellIdentifier pile. If that's the case it picks one off the pile and thus doesn't have to alloc a new one. That way expensive allocing can be kept at a minimum.
I hope this answers your question :)
I am creating an application which uses a web service.And retrieves a list of users and there details like images, user id and there names.I displayed all the information related to users in table view, Thus each of the cell in the table view has an image with the for tables in it. I am using a Custom cell class to create the individual cells. selecting any row in table presents a detail view (using navigation) which show a larger image and all the details related to the particular user i selected.
in customcell and detail view class i am using web view to display image.
But when i run the app the images gets a bit of delay to display and same happens with the detail view.
Is there any alternative so that i can improve the performance of the table view so that i can have smooth scrolling of table view with out any delay in image loading and detail view??
here is the code...
- (UITableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CustomCellIdentifier = #"CustomCellIdentifier ";
CustomCell *cell = (CustomCell *)[tableView
dequeueReusableCellWithIdentifier: CustomCellIdentifier];
if (cell == nil)
{
NSArray *nib = [[NSBundle mainBundle] loadNibNamed:#"CustomCell" owner:self options:nil ];
//cell = [[CustomCell alloc] initwi ];
for (id oneObject in nib)
if ([oneObject isKindOfClass:[CustomCell class]])
cell = (CustomCell *)oneObject;
}
NSUInteger row = [indexPath row];
NSString *imageName = [imgArray objectAtIndex:row];
NSString *completeImageUrl = [[NSString alloc] initWithFormat:#"http://122.160.153.166:201/%#", imageName];
NSURL *url = [NSURL URLWithString:completeImageUrl];
//NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];
NSData *imageData = [[NSData alloc] initWithContentsOfURL:url];
UIImage *image = [UIImage imageWithData:imageData]; /// check to see if we are getting all the arrays such as image array and userId array and name array of same size..
if(image == nil)
{
}
cell.imgView.image = image; /// other wise an execption of out out array range will be shown
[image release];
[imageName release];
//[cell.webView initWithFrame:CGRectZero];
//[cell.webView loadRequest:requestObj];
//cell.webView.frame = CGRectMake(20, 0, 80.0, 64);
cell.userIdLabel.text = (NSString *)[userId objectAtIndex:row];
cell.nameLabel.text = (NSString *)[userName objectAtIndex:row];
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
return cell;
}`
i think problem can be in imgArray array as i am setting it from other class. Where i request the web service and fetched all the data about users .
Any help is greatly appreciated . Thanks in advance
I got the same problem. For that I used EGOImageCache and some thing.
Find this Url for EGOImage
Download files those names starts with "EGO", and add those to your project.
and write the following code where ever you want to put the image:
EGOImageView *imgView = [[EGOImageView alloc] initWithFrame:CGRectMake(50,50,220,360)];
NSString *imageName = [imgArray objectAtIndex:row];
NSString *completeImageUrl = [[NSString alloc] initWithFormat:#"http://122.160.153.166:201/%#", imageName];
NSURL *url = [NSURL URLWithString:completeImageUrl];
imgView.imageUrl = url;
[self.view addSubView:imgView];
Thats it. Use the similar code, where ever you want the image.
At the first time while loading it will take some time to download the image. But later it will cache the image and use it the next time.
Is there any alternative so that i can improve the performance of the table view so that i can have smooth scrolling of table view with out any delay in image loading
For this the answer is Lazy Loading of images in cells
You can implement lazy loading on webviewDidLoad which shows that webview has loaded completely
Using a UIWebView to display a single image is overkill. You should be using NSURLConnection (or one of many alternative HTTP wrappers/libraries) to load the image data and UIImageView to display it in each of your table cells. In my experience, there is no way (or at least no straightforward way) to eliminate the rendering delay when using UIWebView.
Why are you using the webview for displaying the images. Imageview should be used instead. If you are getting the images from the server then you should get those in separate thread and after you receive the images you should reload that particular row.
Some code snippet is like this:
- (UITableViewCell *)cellForRowAtIndexPath:(NSIndexPath *)indexPath
...
...
UIImage *img = (UIImage *)[imagesArray objectAtIndex:indexPath.row];
if(img == nil){
[imgView setImage:temporaryImage];
[NSThread detachNewThreadSelector:#selector(getTheThumnbails:) toTarget:self withObject:indexPath];
}
else
[imgView setImage:img];
for further assistance look at this
Hope this helps.
Thanks,
Madhup
okay finally i removed the uiweb view from my app and used Imaged view and succeed.
i used the link that was given by the developer of the tweetie . here it is link text
i used the ABTableViewCell class and created the whole cell using the code.
The scrolling was very jerky when i executed the app. after applying almost 4 hours and with the help of lazy loading i was able to run my app smoothly. I stored the data which is retrieved from url into an array then applied the concept in tableView:cellForRowAtIndexPath:
method..
Thanks you guys for helping me ...
Three20 has a rich-text table view cell class (TTStyledTextTableCell I think) - should render significantly faster than an embedded UIWebView. You could also roll your own, though that would take a lot longer.