我需要从一个 DispatchTimeInterval
减去一个 NSTimeInterval
(或者 Double
)。
是否有一种标准的方法将 DispatchTimeInterval
转换为 NSTimeInterval
?
我需要从一个 DispatchTimeInterval
减去一个 NSTimeInterval
(或者 Double
)。
是否有一种标准的方法将 DispatchTimeInterval
转换为 NSTimeInterval
?
DispatchTimeInterval
是一个枚举类型:
public enum DispatchTimeInterval : Equatable {
case seconds(Int)
case milliseconds(Int)
case microseconds(Int)
case nanoseconds(Int)
case never
}
您可以使用以下方式初始化DispatchTimeInterval
:
let tenSeconds: DispatchTimeInterval = .seconds(10)
let tenNanoseconds: DispatchTimeInterval = .nanoseconds(10)
if case .seconds(let value) = tenSeconds {
print("DispatchTimeInterval is seconds \(value)")
} else if case .nanoseconds(let value) = tenNanoseconds {
print("DispatchTimeInterval is seconds \(value)")
}
转换函数可能如下所示:
func toDouble(_ interval: DispatchTimeInterval) -> Double? {
var result: Double? = 0
switch interval {
case .seconds(let value):
result = Double(value)
case .milliseconds(let value):
result = Double(value)*0.001
case .microseconds(let value):
result = Double(value)*0.000001
case .nanoseconds(let value):
result = Double(value)*0.000000001
case .never:
result = nil
}
return result
}
更新:
创建 DispatchTimeInterval
的扩展。
extension DispatchTimeInterval {
func toDouble() -> Double? {
var result: Double? = 0
switch self {
case .seconds(let value):
result = Double(value)
case .milliseconds(let value):
result = Double(value)*0.001
case .microseconds(let value):
result = Double(value)*0.000001
case .nanoseconds(let value):
result = Double(value)*0.000000001
case .never:
result = nil
}
return result
}
}
TimeInterval
扩展并在其中添加一个可失败初始化器,该初始化器带有一个DispatchTimeInterval
参数。以下是Swift 5代码示例:import Foundation
extension TimeInterval {
init?(dispatchTimeInterval: DispatchTimeInterval) {
switch dispatchTimeInterval {
case .seconds(let value):
self = Double(value)
case .milliseconds(let value):
self = Double(value) / 1_000
case .microseconds(let value):
self = Double(value) / 1_000_000
case .nanoseconds(let value):
self = Double(value) / 1_000_000_000
case .never:
return nil
}
}
}
使用方法:
let dispatchTimeInterval = DispatchTimeInterval.seconds(5)
let timeInterval = TimeInterval(dispatchTimeInterval: dispatchTimeInterval)
print(String(describing: timeInterval)) // Optional(5.0)
let dispatchTimeInterval = DispatchTimeInterval.milliseconds(30)
let timeInterval = TimeInterval(dispatchTimeInterval: dispatchTimeInterval)
print(String(describing: timeInterval)) // Optional(0.03)
extension DispatchTimeInterval {
var nanoseconds: UInt64 {
let now = DispatchTime.now()
let later = now.advanced(by: self)
return later.uptimeNanoseconds - now.uptimeNanoseconds
}
var timeInterval: TimeInterval {
return Double(nanoseconds) / Double(NSEC_PER_SEC)
}
}
DispatchTimeInterval
设置,并且我在NSTimeInterval
中测量经过的实际时间。我需要将两者相减以获得延迟。 - meaning-matters