CODEWITHSUNDEEP
objective-ciosasynchronousuiimagenstimer
Vinicius Albino
Vinicius Albino

Reputation: 763

Loading and changing images asynchronous

Im loading 4 images from a website asynchronous,and after the loading i change them with a timer,but looks like on the array of the images is always the first image,when i change to another position of the array it contains the same image,dont change at all...

- (void)viewDidLoad 
{
    [super viewDidLoad];

    [self getImages];
}

-(void)getImages
{
    receivedData = [[NSMutableData alloc]init];
    myImages = [[NSMutableArray alloc]init];
    myImagesAdresses = [[NSMutableArray alloc]initWithCapacity:5];

    [myImagesAdresses addObject:@"adress/Images/3.png"];
    [myImagesAdresses addObject:@"adress/Images/2.png"];
    [myImagesAdresses addObject:@"adress/Images/1.png"];
    [myImagesAdresses addObject:@"adress/Images/0.png"];

    [self loadNextImage];
}

-(void)loadNextImage
{
    if([myImagesAdresses count])
    {
        NSURL * imageURL = [NSURL URLWithString:[myImagesAdresses lastObject]];
        NSURLRequest * myRequest = [NSURLRequest requestWithURL:imageURL];
        [[NSURLConnection alloc]initWithRequest:myRequest delegate:self];
        NSLog(@"Start load URL %@",imageURL);
    }
    else {
        [self.theImage setImage:[myImages objectAtIndex:2]];
        [self changeImage];
        NSLog(@"No More Images to Load");
    }
}

-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    [receivedData appendData:data];
}

-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    [myImages addObject:[UIImage imageWithData:[NSData dataWithData:receivedData]]];
    [connection release];
    connection = nil;
    NSLog(@"Image from %@ loaded",[myImagesAdresses lastObject]);
    [myImagesAdresses removeLastObject];
    [self loadNextImage];
}

-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    [connection release];
    connection =nil;
    NSLog(@"Image from %@ not loaded", [myImagesAdresses lastObject]);
    [myImagesAdresses removeLastObject];
    [self loadNextImage];
}

and the code to change the image:

-(void)changeImage
{
    SEL selectorToCall = @selector(change: );

    NSMethodSignature *methodSignature = [[self class] instanceMethodSignatureForSelector:selectorToCall];

    NSInvocation * invocation = [NSInvocation invocationWithMethodSignature:methodSignature];
    [invocation setTarget:self];
    [invocation setSelector:selectorToCall];

    NSTimer * newTimer = [NSTimer scheduledTimerWithTimeInterval:5.0 invocation:invocation repeats:YES];

    self.paintingTimer = newTimer;
}

- (void) change:(NSTimer *)paramTimer
{
    static NSInteger currentElement = 0;
    if(++currentElement == [myImages count]) currentElement = 0;
    [self.theImage setImage:[myImages objectAtIndex:currentElement]];
}

- (void) stopPainting
{
    if (self.paintingTimer != nil){
        [self.paintingTimer invalidate];
    }
}

I dont getting any error,but the image simply dont change...

Upvotes: 0

Views: 578

Answers (2)

Channthoeurn
Channthoeurn

Reputation: 11

You should add this line of code after:

[myImages addObject:[UIImage imageWithData:[NSData dataWithData:receivedData]]];

like this:

[myImages addObject:[UIImage imageWithData:[NSData dataWithData:receivedData]]];
[receivedData setData:nil];

Upvotes: 1

Icydog
Icydog

Reputation: 467

It looks like receivedData is an ivar that you repeatedly append to, but it never gets cleared. So after the first image is received, the second image is appended to it, etc.

After this line, you should empty receivedData:

[myImages addObject:[UIImage imageWithData:[NSData dataWithData:receivedData]]];

Upvotes: 1

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