原视频地址点我，不知道为什么本文在 Hexo 中，会造成其停止工作。折腾半天，重装 Hexo，Time Machine 还原系统，均失败，最后不断删除 post，才对位到问题。
1. Fundamentals
- Diagnostics
- New Warnings
- SDK Improvements
Adoption of new features and best practices:
Nullability qualifiers
Objective-C typed collections
NS_ENUM, NS_OPTIONS, instancetype, @property, etc
Unit Testing
Your code is now built in a “compile for testing” build mode:
Unit tests use
@testable
import MyApp
public and internal symbols are now available
No behavior change for release builds:
Same optimizations
Same insurance against symbol collisions
2. Pattern Matching
Pattern Matching with “if case”
switch bar() {
case .MyEnumCase(let value):where value != 42:
doThing(value)
default: break
}
if case .MyEnumCase(let value) = bar() where value != 42 {
doThing(value)
}
“for ... in” Filtering
for value in mySequence {
if value != "" {
doThing(value)
}
}
for value in mySequence where value != "" {
doThing(value)
}
for case .MyEnumCase(let value) in enumValues {
doThing(value)
}
“if let” Statement: Compound Conditions
func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if let dest = segue.destinationViewController as? BlogViewController
let blogIndex = tableView.indexPathForSelectedRow()?.row
where segue.identifier == blogSegueIdentifier {
“guard” Statement: Compound Conditions
func process(json: AnyObject) -> Either<Person,String> {
guard let name = json["name"] as? String,
let year = json["year"] as? Int else
return .Second(“bad input”)
}
let person = processPerson(name, year)
return .First(person)
}
3. Availability Checking
The Better Approach
@IBOutlet var dropButton: NSButton!
override func awakeFromNib() {
if #available(OSX 10.10.3, *) {
dropButton.springLoaded = true
}
}
4. Protocol Extensions
Methodification
Global generic algorithms are becoming methods
Swift 1:
let x = filter(map(numbers) { $0 * 3 }) { $0 >= 0 }
Swift 2:
let x = numbers.map { $0 * 3 }.filter { $0 >= 0 }
5. Error Handling
Kinds of Error
Trivial errors
- Int(someString)
Detailed, recoverable errors
- File not found
- Network failure
- User cancellation
Logic errors
- Assertions, overflows, NSException, etc.
Works Great with Cocoa
Swift 1:
extension NSData {
class func bookmarkDataWithContentsOfURL(bookmarkFileURL: NSURL,
-> NSData?
}
Swift 2:
extension NSData {
class func bookmarkDataWithContentsOfURL(bookmarkFileURL: NSURL) throws
-> NSData
}
