Creating Delaying each iteration for Loop function in swift-CodePudding

I am new to swift .. I am trying to crate delay and print the delay time like 1 seconds and start printing the next item into list . I got the result but I am not sure make delay of each iteration and print it .. Here is the struct .

struct CartProductResult {
 var id: Int
 var title: String
 var quantity: Int
}
let cartProducts = [
 CartProductResult(id: 1, title: "nike shoe 1", quantity: 5),
 CartProductResult(id: 2, title: "nike shoe 2", quantity: 2),
 CartProductResult(id: 3, title: "soap", quantity: 6)
]

Here is the function ..

func printWithDelay(product1: CartProductResult, product2:
CartProductResult, completion: (@escaping ()-> Void)) {

   completion()
}

Here is the call to the function ..

printWithDelay(product1: cartProducts[0], product2: cartProducts[1])
{
    let seconds = 1.0
    DispatchQueue.main.asyncAfter(deadline: .now()   seconds) {
        print("  Wait 1 second")
        for cartProduct in cartProducts {
            print(cartProduct.id)
        }
        print("Done printing products")
    }

}

Here is the result ,I got..

Here is the expected result ..

CodePudding user response：

You do NOT want to use sleep() on the main thread, as it will appear to "lock up" your app.

Instead, use a repeating Timer -- try this, tap anywhere to start the printWithDelay():

class ViewController: UIViewController {
    
    struct CartProductResult {
        var id: Int
        var title: String
        var quantity: Int
    }
    let cartProducts = [
        CartProductResult(id: 1, title: "nike shoe 1", quantity: 5),
        CartProductResult(id: 2, title: "nike shoe 2", quantity: 2),
        CartProductResult(id: 3, title: "soap", quantity: 6)
    ]
    
    func printOneProduct(_ index: Int) {
        let p = cartProducts[index]
        print("id:", p.id)
    }
    func printWithDelay(products: [CartProductResult], completion: (@escaping ()-> Void)) {
        
        var idx: Int = 0
        
        // we want to print the first product immediately,
        //  then step through the rest 1-second at a time
        printOneProduct(idx)

        Timer.scheduledTimer(withTimeInterval: 1, repeats: true) { timer in
            idx  = 1
            if idx == products.count {
                timer.invalidate()
                completion()
            }
            self.printOneProduct(idx)
        }
    }
    
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        
        printWithDelay(products: cartProducts) {
            print("Done printing products")
        }
        
        // execution continues while products are printing
        
    }
    
}

CodePudding user response：

func printWithDelay(products: [CartProductResult], completion: (@escaping ()-> Void)) {
    for product in products {
        let seconds = 1.0
        sleep(1)
        print("  Wait 1 second")
        print(product.id)
    }
    completion()
}

printWithDelay(products: cartProducts) {
    print("Done printing products")
}