所以我的问题是为什么
例子:
这是:
比...慢:
let _ = this
比this != nil
快?例子:
这是:
let this : Bool? = true //
let start = DispatchTime.now()
for _ in 0...100000000 {
guard this != nil else { continue }
}
let end = DispatchTime.now()
let nanoTime = end.uptimeNanoseconds - start.uptimeNanoseconds
let timeInterval = Double(nanoTime)
print("Time \(timeInterval)")
// Time 5426559135.0
// Time 5428084767.0
// Time 5327325459.0
比...慢:
let this : Bool? = true //
let start = DispatchTime.now()
for _ in 0...100000000 {
guard let _ = this else { continue }
}
let end = DispatchTime.now()
let nanoTime = end.uptimeNanoseconds - start.uptimeNanoseconds
let timeInterval = Double(nanoTime)
print("Time \(timeInterval)")
// Time 257045414.0
// Time 261933863.0
// Time 263465919.0