Protocols - apple developer

@objc protocol CounterDataSource {
    @objc optional func increment(forCount count: Int) -> Int
    @objc optional var fixedIncrement: Int { get }
}

• 我朋友说还有一种方式就是给协议写一个默认的实现，如下代码

protocol SSPSelectStockDelegate: NSObjectProtocol {
    func onSelectStock(model: SSPStockModel)
}

extension SSPSelectStockDelegate {
    func onSelectStock(model: SSPStockModel) {
        
    }
}