-performSelector : withObject : afterDelay :와 같이 지연 후 블록을 어떻게 트리거합니까?

-performSelector : withObject : afterDelay :와 같이 지연 후 블록을 어떻게 트리거합니까?

---

사용하는 것과 같이, 지연 후 기본 매개 변수 블록을 호출하는 방법이 performSelector:withObject:afterDelay:있지만, 같은 인수는 int/ double/ float?

---

나는 당신이 찾고 있다고 생각합니다 dispatch_after(). 블록이 매개 변수를 허용하지 않도록 요구하지만 블록이 로컬 범위에서 해당 변수를 캡처하도록 할 수 있습니다.

int parameter1 = 12;
float parameter2 = 144.1;

// Delay execution of my block for 10 seconds.
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 10 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{
    NSLog(@"parameter1: %d parameter2: %f", parameter1, parameter2);
});

더보기 : https://developer.apple.com/documentation/dispatch/1452876-dispatch_after

---

dispatch_after나중에 블록을 호출하는 데 사용할 수 있습니다 . 엑스 코드에서 입력을 시작 dispatch_after하고 명중 Enter다음에 자동 완성 :

다음은 "인수"로 두 개의 부동 소수점을 사용한 예입니다. 어떤 유형의 매크로에도 의존 할 필요가 없으며 코드의 의도는 매우 분명합니다.

스위프트 3, 스위프트 4

let time1 = 8.23
let time2 = 3.42

// Delay 2 seconds
DispatchQueue.main.asyncAfter(deadline: .now() + 2.0) {
    print("Sum of times: \(time1 + time2)")
}

스위프트 2

let time1 = 8.23
let time2 = 3.42

// Delay 2 seconds
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, Int64(2.0 * Double(NSEC_PER_SEC))), dispatch_get_main_queue()) { () -> Void in
        println("Sum of times: \(time1 + time2)")
}

목표 C

CGFloat time1 = 3.49;
CGFloat time2 = 8.13;

// Delay 2 seconds
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
    CGFloat newTime = time1 + time2;
    NSLog(@"New time: %f", newTime);
});

---

Xcode 내장 코드 조각 라이브러리를 사용하는 것은 어떻습니까?

Swift 업데이트 :

많은 찬성 투표를 통해이 답변을 업데이트했습니다.

내장 Xcode 코드 조각 라이브러리에는 언어 dispatch_after만 objective-c있습니다. .NET 용 사용자 지정 코드 조각 을 만들 수도 있습니다 Swift.

이것을 Xcode로 작성하십시오.

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, Int64(<#delayInSeconds#> * Double(NSEC_PER_SEC))), dispatch_get_main_queue(), {
        <#code to be executed after a specified delay#>
    })

이 코드를 코드 조각 라이브러리 영역에 끌어다 놓습니다.

코드 스 니펫 목록 하단에라는 새 엔티티가 있습니다 My Code Snippet. 제목을 편집하십시오. Xcode를 입력 할 때 제안을 받으려면 Completion Shortcut.

자세한 내용은 CreatingaCustomCodeSnippet을 참조하십시오 .

Swift 3 업데이트

이 코드를 코드 조각 라이브러리 영역에 끌어다 놓습니다.

DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(<#delayInSeconds#>)) {
    <#code to be executed after a specified delay#>
}

---

Jaime Cham의 답변을 확장하여 아래와 같이 NSObject + Blocks 범주를 만들었습니다. 이 방법이 기존 performSelector:NSObject 방법 과 더 잘 일치한다고 느꼈습니다.

NSObject + Blocks.h

#import <Foundation/Foundation.h>

@interface NSObject (Blocks)

- (void)performBlock:(void (^)())block afterDelay:(NSTimeInterval)delay;

@end

NSObject + Blocks.m

#import "NSObject+Blocks.h"

@implementation NSObject (Blocks)

- (void)performBlock:(void (^)())block
{
    block();
}

- (void)performBlock:(void (^)())block afterDelay:(NSTimeInterval)delay
{
    void (^block_)() = [block copy]; // autorelease this if you're not using ARC
    [self performSelector:@selector(performBlock:) withObject:block_ afterDelay:delay];
}

@end

다음과 같이 사용하십시오.

[anyObject performBlock:^{
    [anotherObject doYourThings:stuff];
} afterDelay:0.15];

---

GCD, 어딘가에있는 클래스 (예 : "Util") 또는 Category on Object를 사용하는 것보다 간단 할 수 있습니다.

+ (void)runBlock:(void (^)())block
{
    block();
}
+ (void)runAfterDelay:(CGFloat)delay block:(void (^)())block 
{
    void (^block_)() = [[block copy] autorelease];
    [self performSelector:@selector(runBlock:) withObject:block_ afterDelay:delay];
}

사용하려면 :

[Util runAfterDelay:2 block:^{
    NSLog(@"two seconds later!");
}];

---

Swift의 경우 dispatch_after메서드를 사용하여 특별하지 않은 전역 함수를 만들었습니다 . 읽기 쉽고 사용하기 쉽기 때문에 더 좋아합니다.

func performBlock(block:() -> Void, afterDelay delay:NSTimeInterval){
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, Int64(delay * Double(NSEC_PER_SEC))), dispatch_get_main_queue(), block)
}

다음과 같이 사용할 수 있습니다.

performBlock({ () -> Void in
    // Perform actions
}, afterDelay: 0.3)

---

여기 내 2 센트 = 5 가지 방법이 있습니다.)

나는 이러한 세부 사항을 캡슐화하고 AppCode가 내 문장을 완성하는 방법을 알려주는 것을 좋아합니다.

void dispatch_after_delay(float delayInSeconds, dispatch_queue_t queue, dispatch_block_t block) {
    dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
    dispatch_after(popTime, queue, block);
}

void dispatch_after_delay_on_main_queue(float delayInSeconds, dispatch_block_t block) {
    dispatch_queue_t queue = dispatch_get_main_queue();
    dispatch_after_delay(delayInSeconds, queue, block);
}

void dispatch_async_on_high_priority_queue(dispatch_block_t block) {
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), block);
}

void dispatch_async_on_background_queue(dispatch_block_t block) {
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), block);
}

void dispatch_async_on_main_queue(dispatch_block_t block) {
    dispatch_async(dispatch_get_main_queue(), block);
}

---

PerformSelector : WithObject는 항상 객체를 취하므로 int / double / float 등과 같은 인수를 전달하기 위해 ..... 이와 같은 것을 사용할 수 있습니다.

// NSNumber는 객체입니다 ..

[self performSelector:@selector(setUserAlphaNumber:)
     withObject: [NSNumber numberWithFloat: 1.0f]       
     afterDelay:1.5];



-(void) setUserAlphaNumber: (NSNumber*) number{

     [txtUsername setAlpha: [number floatValue] ];

}

같은 방법으로 [NSNumber numberWithInt :] 등을 사용할 수 있으며 수신 방법에서 숫자를 [number int] 또는 [number double] 형식으로 변환 할 수 있습니다.

---

dispatch_after 함수는 주어진 시간이 지나면 디스패치 큐에 블록 객체를 디스패치합니다. 2.0 초 후에 UI 관련 작업을 수행하려면 아래 코드를 사용하십시오.

            let delay = 2.0
            let delayInNanoSeconds = dispatch_time(DISPATCH_TIME_NOW, Int64(delay * Double(NSEC_PER_SEC)))
            let mainQueue = dispatch_get_main_queue()

            dispatch_after(delayInNanoSeconds, mainQueue, {

                print("Some UI related task after delay")
            })

신속한 3.0 :

            let dispatchTime: DispatchTime = DispatchTime.now() + Double(Int64(2.0 * Double(NSEC_PER_SEC))) / Double(NSEC_PER_SEC)
            DispatchQueue.main.asyncAfter(deadline: dispatchTime, execute: {

          })

---

지연 후 작업을 대기열에 넣는 Swift 3 방법은 다음과 같습니다.

DispatchQueue.main.asyncAfter(
  DispatchTime.now() + DispatchTimeInterval.seconds(2)) {
    // do work
}

---

다음 은 성가신 GCD 호출을 반복 하는 것을 방지 하는 편리한 도우미입니다 .

public func delay(bySeconds seconds: Double, dispatchLevel: DispatchLevel = .main, closure: @escaping () -> Void) {
    let dispatchTime = DispatchTime.now() + seconds
    dispatchLevel.dispatchQueue.asyncAfter(deadline: dispatchTime, execute: closure)
}

public enum DispatchLevel {
    case main, userInteractive, userInitiated, utility, background
    var dispatchQueue: DispatchQueue {
        switch self {
        case .main:                 return DispatchQueue.main
        case .userInteractive:      return DispatchQueue.global(qos: .userInteractive)
        case .userInitiated:        return DispatchQueue.global(qos: .userInitiated)
        case .utility:              return DispatchQueue.global(qos: .utility)
        case .background:           return DispatchQueue.global(qos: .background)
        }
    }
}

이제 다음 과 같이 Main 스레드에서 코드를 지연시키기 만하면됩니다 .

delay(bySeconds: 1.5) { 
    // delayed code
}

코드를 다른 스레드 로 지연 시키 려면 다음을 수행 하십시오 .

delay(bySeconds: 1.5, dispatchLevel: .background) { 
    // delayed code that will run on background thread
}

---

If you prefer a Framework that also has some more handy features then checkout HandySwift. You can add it to your project via Carthage then use it exactly like in the examples above:

import HandySwift    

delay(bySeconds: 1.5) { 
    // delayed code
}

---

There's a nice one in the BlocksKit framework.

BlocksKit

(and the class)

BBlocksKit.m

---

In swift 3, We can simply use DispatchQueue.main.asyncAfter function to trigger any function or action after the delay of 'n' seconds. Here in code we have set delay after 1 second. You call any function inside the body of this function which will trigger after the delay of 1 second.

let when = DispatchTime.now() + 1
DispatchQueue.main.asyncAfter(deadline: when) {

    // Trigger the function/action after the delay of 1Sec

}

---

You can either wrap the argument in your own class, or wrap the method call in a method that doesn't need to be passed in the primitive type. Then call that method after your delay, and within that method perform the selector you wish to perform.

---

Here is how you can trigger a block after a delay in Swift:

runThisAfterDelay(seconds: 2) { () -> () in
    print("Prints this 2 seconds later in main queue")
}

/// EZSwiftExtensions
func runThisAfterDelay(seconds seconds: Double, after: () -> ()) {
    let time = dispatch_time(DISPATCH_TIME_NOW, Int64(seconds * Double(NSEC_PER_SEC)))
    dispatch_after(time, dispatch_get_main_queue(), after)
}

Its included as a standard function in my repo.

---

Swift 3 & Xcode 8.3.2

This code will help you, i add an explanation too

// Create custom class, this will make your life easier
class CustomDelay {

    static let cd = CustomDelay()

    // This is your custom delay function
    func runAfterDelay(_ delay:Double, closure:@escaping ()->()) {
        let when = DispatchTime.now() + delay
        DispatchQueue.main.asyncAfter(deadline: when, execute: closure)
    }
}


// here how to use it (Example 1)
class YourViewController: UIViewController {

    // example delay time 2 second
    let delayTime = 2.0

    override func viewDidLoad() {
        super.viewDidLoad()

        CustomDelay.cd.runAfterDelay(delayTime) {
            // This func will run after 2 second
            // Update your UI here, u don't need to worry to bring this to the main thread because your CustomDelay already make this to main thread automatically :)
            self.runFunc()
        }
    }

    // example function 1
    func runFunc() {
        // do your method 1 here
    }
}

// here how to use it (Example 2)
class YourSecondViewController: UIViewController {

    // let say you want to user run function shoot after 3 second they tap a button

    // Create a button (This is programatically, you can create with storyboard too)
    let shootButton: UIButton = {
        let button = UIButton(type: .system)
        button.frame = CGRect(x: 15, y: 15, width: 40, height: 40) // Customize where do you want to put your button inside your ui
        button.setTitle("Shoot", for: .normal)
        button.translatesAutoresizingMaskIntoConstraints = false
        return button
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        // create an action selector when user tap shoot button
        shootButton.addTarget(self, action: #selector(shoot), for: .touchUpInside)   
    }

    // example shoot function
    func shoot() {
        // example delay time 3 second then shoot
        let delayTime = 3.0

        // delay a shoot after 3 second
        CustomDelay.cd.runAfterDelay(delayTime) {
            // your shoot method here
            // Update your UI here, u don't need to worry to bring this to the main thread because your CustomDelay already make this to main thread automatically :)
        }
    }   
}

---

I believe the author is not asking how to wait for a fractional time (delay), but instead how to pass a scalar as argument of the selector (withObject:) and the fastest way in modern objective C is:

[obj performSelector:...  withObject:@(0.123123123) afterDelay:10]

your selector have to change its parameter to NSNumber, and retrieve the value using a selector like floatValue or doubleValue

---

Xcode 10.2 and Swift 5 and above

DispatchQueue.main.asyncAfter(deadline: .now() + 2, execute: {
   // code to execute                 
})

참고 URL : https://stackoverflow.com/questions/4139219/how-do-you-trigger-a-block-after-a-delay-like-performselectorwithobjectafter