Load images Asynchrously- objective c

Load images Asynchrously- objective c

- (void)downloadImageWithURL:(NSURL *)url completionBlock:(void (^)(BOOL succeeded, UIImage *image))completionBlock
{
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
if ( !error )
{
UIImage *image = [[UIImage alloc] initWithData:data];
completionBlock(YES,image);
} else{
completionBlock(NO,nil);
}
}];
}

//// call the function where u want to display image

[self downloadImageWithURL:[img_url objectAtIndex:i] completionBlock:^(BOOL succeeded, UIImage *image) {
if (succeeded) {
// change the image in the cell
if(image==NULL)
{

}
else{

[array addobject:image];

}

}

}];

Image slider using scrollView and timer

- (void)setupScrollView:(UIScrollView*)scrMain {

    // we have 10 images here.

    // we will add all images into a scrollView & set the appropriate size.

    

    for (int i=1; i<=10; i++) {

        // create image

        UIImage *image = [UIImage imageNamed:[NSString stringWithFormat:@"sti%02i.jpeg",i]];

        // create imageView

        UIImageView *imgV = [[UIImageView alloc] initWithFrame:CGRectMake((i-1)*scrMain.frame.size.width, 0, scrMain.frame.size.width, scrMain.frame.size.height)];

        // set scale to fill

        imgV.contentMode=UIViewContentModeScaleToFill;

        // set image

        [imgV setImage:image];

        // apply tag to access in future

        imgV.tag=i+1;

        // add to scrollView

        [scrMain addSubview:imgV];

    }

    // set the content size to 10 image width

    [scrMain setContentSize:CGSizeMake(scrMain.frame.size.width*10, scrMain.frame.size.height)];

    // enable timer after each 2 seconds for scrolling.

    [NSTimer scheduledTimerWithTimeInterval:2 target:self selector:@selector(scrollingTimer) userInfo:nil repeats:YES];

}

- (void)scrollingTimer {

    // access the scroll view with the tag

    UIScrollView *scrMain = (UIScrollView*) [self.view viewWithTag:1];

    // same way, access pagecontroll access

    UIPageControl *pgCtr = (UIPageControl*) [self.view viewWithTag:12];

    // get the current offset ( which page is being displayed )

    CGFloat contentOffset = scrMain.contentOffset.x;

    // calculate next page to display

    int nextPage = (int)(contentOffset/scrMain.frame.size.width) + 1 ;

    // if page is not 10, display it

    if( nextPage!=10 )  {

        [scrMain scrollRectToVisible:CGRectMake(nextPage*scrMain.frame.size.width, 0, scrMain.frame.size.width, scrMain.frame.size.height) animated:YES];

        pgCtr.currentPage=nextPage;

        // else start sliding form 1 :)

    } else {

        [scrMain scrollRectToVisible:CGRectMake(0, 0, scrMain.frame.size.width, scrMain.frame.size.height) animated:YES];

        pgCtr.currentPage=0;

    }

}

Set objectForKey in mutable array

NSMutableArray *nearby = [[NSMutableArray alloc]init];

[nearby addObject:[mutableArray objectAtIndex:x]];

            

[[nearby objectAtIndex:x] setValue:[NSNumber numberWithFloat:distance] forKey:@"Km"];

Sort mutableArray according to the "Km" with accending

NSSortDescriptor * sort = [[NSSortDescriptor alloc] initWithKey:@"Km" ascending:YES];

NSArray *sa = [nearby sortedArrayUsingDescriptors:[NSArray arrayWithObject:sort]];

Class method and Object method.

@interface TheClassA : NSObject

+ (TypeA)classMethod;

- (TypeB)objectMethod;

@end

@implementation TheClassA

+ (TypeA)classMethod

{

}

- (TypeB)objectMethod

{

}

@end



main()

{

    [TheClassA classMethod]; // Correct!!!

    [TheClassA objectMethod]; // Wrong!!!

    

    TheClassA *obj = [[TheClassA alloc] init];

    [obj classMethod]; // Wrong;

    [obj objectMethod]; // Correct;

    [obj.class classMethod]; // Correct

    [obj.class objectMethod]; // Wrong

}