iOS -- Working with Images

Reading Image Data

 1. UIImage Convenience Methods
     myImage = [UIImage imageNamed:@"icon.png"];

 2. Finding Images in the Sandbox
     NSArray *paths = [NSSearchPathForDirectoriesInDomains(
     NSDocumentDirectory, NSUserDomainMask, YES);
     return [paths lastObject];

     NSString *documentsFolder()
    {
      return [NSHomeDirectory()
      stringByAppendingPathComponent:@"Documents"];
     }

    path = [documentsFolder() stringByAppendingPathComponent:@"image.png"];
    return [UIImage imageWithContentsOfFile:path];


 3.Loading Images from URLs
    NSURL *url = [NSURL URLWithString:
    @"http://image.weather.com/images/maps/current/curwx_600x405.jpg"];

    UIImage *img = [UIImage imageWithData:
    [NSData dataWithContentsOfURL:url]];


    load itself asynchronously without blocking the main thread


   // Create an asynchronous background queue

    NSOperationQueue *queue = [[NSOperationQueue alloc] init];
    [queue addOperationWithBlock:
    ^{
      // Load the weather data

      NSURL *weatherURL = [NSURL URLWithString:@"http://image.weather.com/images\
      /maps/current/curwx_600x405.jpg"];

      NSData *imageData = [NSData dataWithContentsOfURL:weatherURL];

     // Update the image on the main thread using the main queue

    [[NSOperationQueue mainQueue] addOperationWithBlock:^{

    UIImage *weatherImage = [UIImage imageWithData:imageData];

    imageView.image = weatherImage;}];