iOS 开发OTG代码示例

iOS开发中的OTG（On-The-Go）功能是指通过Lightning接口或USB-C接口，使iOS设备能够连接外部USB设备，如USB闪存驱动器、键盘、鼠标等。下面是一个简单的iOS开发OTG代码示例：

首先，需要导入ExternalAccessory框架，并在Info.plist文件中添加相应的权限描述。

import ExternalAccessory

class ViewController: UIViewController, EAAccessoryDelegate, EASessionDelegate {
    var session: EASession?
    var accessory: EAAccessory?
    var inputStream: InputStream?
    var outputStream: OutputStream?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 检测已连接的外部设备
        NotificationCenter.default.addObserver(self, selector: #selector(accessoryConnected), name: NSNotification.Name.EAAccessoryDidConnect, object: nil)
        EAAccessoryManager.shared().registerForLocalNotifications()
        
        // 连接指定的外部设备
        if let connectedAccessories = EAAccessoryManager.shared().connectedAccessories {
            for accessory in connectedAccessories {
                if accessory.protocolStrings.contains("com.yourprotocol") {
                    self.accessory = accessory
                    self.openSession()
                    break
                }
            }
        }
    }
    
    @objc func accessoryConnected(notification: NSNotification) {
        if let accessory = notification.userInfo?[EAAccessoryKey] as? EAAccessory {
            if accessory.protocolStrings.contains("com.yourprotocol") {
                self.accessory = accessory
                self.openSession()
            }
        }
    }
    
    func openSession() {
        guard let accessory = self.accessory else { return }
        
        self.session = EASession(accessory: accessory, forProtocol: "com.yourprotocol")
        guard let session = self.session else { return }
        
        self.inputStream = session.inputStream
        self.outputStream = session.outputStream
        
        self.inputStream?.delegate = self
        self.outputStream?.delegate = self
        
        self.inputStream?.schedule(in: .current, forMode: .default)
        self.outputStream?.schedule(in: .current, forMode: .default)
        
        self.inputStream?.open()
        self.outputStream?.open()
    }
    
    // 发送数据
    func sendData(data: Data) {
        guard let outputStream = self.outputStream else { return }
        
        let bytesWritten = outputStream.write((data as NSData).bytes.bindMemory(to: UInt8.self, capacity: data.count), maxLength: data.count)
        
        if bytesWritten == -1 {
            // 发送失败
        } else if bytesWritten < data.count {
            // 发送未完成
        } else {
            // 发送成功
        }
    }
    
    // 接收数据
    func stream(_ aStream: Stream, handle eventCode: Stream.Event) {
        if eventCode == .hasBytesAvailable {
            guard let inputStream = self.inputStream else { return }
            
            var buffer = [UInt8](repeating: 0, count: 1024)
            let bytesRead = inputStream.read(&buffer, maxLength: buffer.count)
            
            if bytesRead > 0 {
                let receivedData = Data(bytes: buffer, count: bytesRead)
                // 处理接收到的数据
            }
        }
    }
    
    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        
        self.inputStream?.close()
        self.outputStream?.close()
        
        self.inputStream?.remove(from: .current, forMode: .default)
        self.outputStream?.remove(from: .current, forMode: .default)
        
        self.inputStream?.delegate = nil
        self.outputStream?.delegate = nil
        
        self.inputStream = nil
        self.outputStream = nil
        
        self.session?.close()
        self.session = nil
    }
}

这是一个简单的iOS开发OTG代码示例，其中包括了连接外部设备、发送数据和接收数据的基本操作。你可以根据自己的需求进行修改和扩展。