The document discusses new features in Swift 2.0 including checking API availability, synthesized headers, protocol extensions, error handling improvements, and more. It provides code examples for checking API availability using #available, generating synthesized headers, using protocol extensions to provide default implementations, and the new try/catch syntax for error handling.

1. • Checking API Availability
• Synthesized Headers
• Protocol Extension
• Error Handling
• And more…
What’s New in Swift 2.0

2. Apple always rolls out new API’s and classes
throughout the year.
How do we check for API & Class availability?
Checking API Availability in Swift

3. The old way:
if NSClassFromString("SFSafariViewControler") != nil {
let eHAdviceVC = SFSafariViewController(URL: url, entersReaderIfAvailable: true)
eHAdviceVC.delegate = self
presentViewController(eHAdviceVC, animated: true, completion: nil)
} else {
let eHAdviceVC = eHAdviceViewController(URL: url);
presentViewController(eHAdviceVC, animated: true, completion: nil)
}
Checking API Availability in Swift

4. Checking API Availability in Swift
The new way:
if #available(iOS 9, OS X 10.10, watchOS 2, *) {
let eHAdviceVC = SFSafariViewController(URL: url, entersReaderIfAvailable: true)
eHAdviceVC.delegate = self
presentViewController(eHAdviceVC, animated: true, completion: nil)
} else {
let eHAdviceVC = eHAdviceViewController();
presentViewController(eHAdviceVC, animated: true, completion: nil)
}

5. Synthesized header files:
Xcode 7 scans through your code and produces virtual header files
that summarize the exposed methods with none of the code
Documentation - Similar to Apple's own classes
How to generate synthesized headers in Xcode 7?
Xcode 7, go to Navigate > Generated Interface.
Synthesized Headers

6. Synthesized Headers
extension NSURLRequest: URLRequestConvertible {
public var URLRequest: NSURLRequest
}
func URLRequest(method: Method, URL: URLStringConvertible) -> NSURLRequest
/**
Creates a request using the shared manager instance for the specified method, URL string, parameters, and parameter
encoding.
:param: method The HTTP method.
:param: URLString The URL string.
:param: parameters The parameters. `nil` by default.
:param: encoding The parameter encoding. `.URL` by default.
:returns: The created request.
*/
public func request(method: Method, URLString: URLStringConvertible, parameters: [String: AnyObject]? = nil, encoding:
ParameterEncoding = .URL) -> Request
/**
Creates a request using the shared manager instance for the specified URL request.
If `startRequestsImmediately` is `true`, the request will have `resume()` called before being returned.
:param: URLRequest The URL request
:returns: The created request.
*

7. Protocol Extensions
Protocols can be extended to provide method
and property implementations to conforming
types.
You can use protocol extensions to provide a
default implementation to any method or property
requirement of that protocol.

8. Protocol Extensions
Example:
let ageOfEmployees: [Int?] = [30, 32, nil, 45, 50, 12, 8, 25, nil]
extension SequenceType where Generator.Element: OptionalType {
var purify: [Self.Generator.Element.T] {
return self.map { $0.optional }.filter { $0 != nil }.map { $0! }
}
}
let ageOfEmployees: [Int?] = [30, 32, nil, 45, 50, 12, 8, 25, nil]
ageOfEmployees.purify
[30, 32, 45, 50, 12, 8, 25]

9. Error Handling
Example:
func refreshActivityFeed() {
let refreshToken = login()
loadActivityFeed(refreshToken)
updateUI()
}

10. Error Handling
The Old Way:
func refreshActivityFeed() {
let refreshToken:String? = login(username, error:&error)
if (error != nil) {
if let error = error {
switch (error.code) {
case ERROR_UNAUTHORIZED:
showLoginVC()
case ERROR_FORBIDDEN:
showErrorAlert()
case ERROR_NOT_FOUND:
showLoginVC()
default:
showErrorAlert()
}
}
} else {
// Fetch the most recent activity feeds from the server
// Parse and prepare data structure
// Update UI
loadActivityFeed(refreshToken!)
updateUI()
}
}

11. The New Way:
func refreshActivityFeed() {
do
{
let refreshToken = try login(username)
loadActivityFeed(refreshToken)
updateUI()
} catch (LoginError.ERROR_UNAUTHORIZED) {
showLoginVC()
} catch (LoginError.ERROR_FORBIDDEN) {
showErrorAlert()
} catch (LoginError.ERROR_NOT_FOUND) {
showLoginVC()
} catch {
showErrorAlert()
}
}
Error Handling

12. Error Handling
Representing Errors
• ErrorType is a protocol in the Swift Standard Library
• Any type that conforms to ErrorType can be thrown and caught
• Can make your own types conform as well
• enum is great for groups of related errors
enum LoginError : ErrorType {
case ERROR_UNAUTHORIZED
case ERROR_FORBIDDEN
case ERROR_NOT_FOUND
case ERROR_NOT_ALLOWED
case ErrorWithMessage(code: Int, message: String)
}

13. Throwing Errors:
enum VendingMachineError: ErrorType {
case InvalidSelection
case InsufficientFunds(required: Double)
case OutOfStock
}
func purchaseItemFromVendingMachine(item: VendingItem) throws -> Bool {
if item.count() > 0 {
// .....
return true
} else {
throw VendingMachineError.OutOfStock
}
}
Error Handling

14. Catching and Handling Errors:
func refreshActivityFeed() {
do
{
let refreshToken = try loginWithUserName(username)
loadActivityFeed(refreshToken)
updateUI()
} catch (LoginError.ERROR_UNAUTHORIZED) {
showLoginVC()
} catch (LoginError.ERROR_FORBIDDEN) {
showErrorAlert()
} catch (LoginError.ERROR_NOT_FOUND) {
showLoginVC()
} catch {
showErrorAlert()
}
}
Error Handling

15. Disabling Error Propagation:
try! loadConfiguration()
Error Handling

16. Specifying Cleanup Actions:
func processFile(filename: String) throws {
if exists(filename) {
do {
let file = try open(filename)
defer {
close(file)
}
while let line = try file.readline() {
...
}
} catch {
...
}
}
}
Error Handling