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| // copy from https://www.craftappco.com/blog/2018/5/30/simple-throttling-in-swift | |
| class Throttler { | |
| private var workItem: DispatchWorkItem = DispatchWorkItem(block: {}) | |
| private var previousRun: Date = Date.distantPast | |
| private let queue: DispatchQueue | |
| private let minimumDelay: TimeInterval | |
| init(minimumDelay: TimeInterval, queue: DispatchQueue = DispatchQueue.main) { | |
| self.minimumDelay = minimumDelay | |
| self.queue = queue | |
| } | |
| func throttle(_ block: @escaping () -> Void) { | |
| // Cancel any existing work item if it has not yet executed | |
| workItem.cancel() | |
| // Re-assign workItem with the new block task, resetting the previousRun time when it executes | |
| workItem = DispatchWorkItem() { | |
| [weak self] in | |
| self?.previousRun = Date() | |
| block() | |
| } | |
| // If the time since the previous run is more than the required minimum delay | |
| // => execute the workItem immediately | |
| // else | |
| // => delay the workItem execution by the minimum delay time | |
| let delay = previousRun.timeIntervalSinceNow > minimumDelay ? 0 : minimumDelay | |
| queue.asyncAfter(deadline: .now() + Double(delay), execute: workItem) | |
| } | |
| } | |
| /// usage | |
| let throttler = Throttler(minimumDelay: 0.5) | |
| func frequentlyCalledMethod() { | |
| // Throttling our computationally expensive task will ensure | |
| // that it is only run once after 0.5 seconds have elapsed since last being requested, | |
| // preventing excessive computation in the case that this method is called with high frequency | |
| throttler.throttle { | |
| computationallyExpensiveTask() | |
| } | |
| } | |
| func computationallyExpensiveTask() { | |
| } | |
| /// altnative | |
| import Foundation | |
| import UIKit | |
| public extension UIControl { | |
| /// Default debounce delay for UIButton taps. Allows delay to be updated globally. | |
| @objc static var debounceDelay: Double = 0.5 | |
| /// Debounces button taps with the specified delay. | |
| @objc func debounce(delay: Double = UIControl.debounceDelay, siblings: [UIControl] = []) { | |
| let buttons = [self] + siblings | |
| buttons.forEach { $0.isEnabled = false } | |
| let deadline = DispatchTime.now() + delay | |
| DispatchQueue.main.asyncAfter(deadline: deadline) { | |
| buttons.forEach { $0.isEnabled = true } | |
| } | |
| } | |
| } |
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