Apple has added many features to its iOS7 operating system. Few are mentioned below:-

   Story Board in iOS7 app will have to ask user's permission to access the mic.
   The user can use [NSArray firstObject]; just like lastObject in previous Xcode versions.
         for example =  NSArray *arr = @[];
        id item = [arr firstObject];

   instancetype is used in method declarations to indicate the return type to the compiler; it indicates that the object returned will be an instance of the class on which the method is called. Its better than returning id as the compiler can do a bit of error-checking against return types at compile time, as opposed to only detecting these issues at run time. It also does away with the need to cast the type of the returned value when calling methods on subclasses.

   UIImage now has a read-only property named renderingMode as well as a new method imageWithRenderingMode: which uses the new enum UIImageRenderingMode containing the following possible values:

    UIImageRenderingModeAutomatic;
    UIImageRenderingModeAlwaysOriginal;
    UIImageRenderingModeAlwaysTemplate;
for example:-

            UIImage *img = [UIImage imageNamed:@"myimage"];
            img = [img imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];

   Texture colors are no longer available in ios7.
   UIButtonTypeRoundRect  has been replaced by UIButtonTypeSystem.
   Check with wireless routes are available.
   ios7 introduced iCloud Keychain to provide synchronization of passwords and other sensitive data via iCloud. This feature is available to developers via the kSecAttrSynchronizable key in the Keychain attributes dictionary.

   iOS 7 adds two new face detection features to Core Image: CIDetectorEyeBlink and CIDetectorSmile. In plain English, that means you can now detect smiles and blinks in a photo! 


   Asset catalogs
   iOS 7 introduces a new feature to help organize your images: asset catalogs. An asset catalog is a special folder for your images managed by Xcode that makes it easy to associate multiple versions of an image (i.e. normal version, Retina version, 4-inch iPhone version, iPad version, etc) with a single filename.
From the Xcode menu bar, choose File  New  File From the sidebar choose Resource, and then Asset     Catalog.

An asset catalog makes it easier to keep track of your images, while ensuring the app will load the images as efficiently as possible. You can store any images you wish in this catalog, including your app icons and launch images. Loading images from an asset catalog works no differently than it did in a pre-iOS 7 universe. When you ask UIImage to load an image file, it now looks inside the asset catalog first.