前言
Runtime介紹
學習一個東西至少要先知道它是個啥，你一定聽說過“運行時是 Objective-C 的一個特色”，這里的“運行時”就是指 runtime 了。
老的方式initialize現在已經不適用了，需要用新的方式代替。
思路: 定義一個啟動的協議，在app完成啟動的方法里把需要做method swizzle的類跑一邊協議的方法
第一種
1、Step One
protocol SelfAware: class { static func awake() } class NothingToSeeHere { static func harmlessFunction() { let typeCount = Int(objc_getClassList(nil, 0)) let types = UnsafeMutablePointer<AnyClass?>.allocate(capacity: typeCount) let autoreleasingTypes = AutoreleasingUnsafeMutablePointer<AnyClass?>(types) objc_getClassList(autoreleasingTypes, Int32(typeCount)) for index in 0 ..< typeCount { (types[index] as? SelfAware.Type)?.awake() } types.deallocate(capacity: typeCount) } }2、step two
extension UIApplication { private static let runOnce: Void = { NothingToSeeHere.harmlessFunction() }() override open var next: UIResponder? { // Called before applicationDidFinishLaunching UIApplication.runOnce return super.next } } 3、step three
遵循協議SelfAware,實現awake()
第二種(類似第一種)
1、創建一個swizzle注入的協議
public protocol SwizzlingInjection: class { static func inject()}2、創建swizzle helper
open class SwizzlingManager { //只會調用一次的方法 private static let doOnce: Any? = { UIViewController.inject() return nil }() open static func enableInjection() { _ = SwizzlingManager.doOnce }}3、給UIApplication 創建分類調用那個一次方法
extension UIApplication{ open override var next: UIResponder?{ SwizzlingManager.enableInjection() return super.next }}4、在你需要的類中遵循注入協議
extension UIViewController: SwizzlingInjection{ public static func inject() { //確保不是子類 guard self === UIViewController.self else { return } DispatchQueue.once(token: "com.moglo.urmoji.UIViewController") { //do swizzle method } }}once只執行一次的方法
public extension DispatchQueue { private static var _onceTracker = [String]() public class func once(file: String = #file, function: String = #function, line: Int = #line, block:()->Void) { let token = file + ":" + function + ":" + String(line) once(token: token, block: block) } /** Executes a block of code, associated with a unique token, only once. The code is thread safe and will only execute the code once even in the presence of multithreaded calls. - parameter token: A unique reverse DNS style name such as com.vectorform.<name> or a GUID - parameter block: Block to execute once */ public class func once(token: String, block:()->Void) { objc_sync_enter(self) defer { objc_sync_exit(self) } if _onceTracker.contains(token) { return } _onceTracker.append(token) block() } //delay typealias Task = (_ cancel : Bool) -> Void @discardableResult static func delay(time : TimeInterval, task: @escaping () -> ()) -> Task? { func dispatch_later(block : @escaping () -> ()) { DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + time , execute: block) } var closure : (() -> ())? = task var result : Task? let delayedClosure : Task = { cancel in if let internalClosure = closure { if cancel == false { DispatchQueue.main.async(execute: internalClosure) } } closure = nil result = nil } result = delayedClosure dispatch_later { () -> () in if let delayedClosure = result { delayedClosure(false) } } return result } static func cancel(task : Task?) { task?(true) }}總結
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