swift - 打印不显示在控制台中(快速)

Question

我的代码不在控制台中打印。我尝试了几种方法，但没有任何效果。下面的代码是可能导致打印未在控制台中显示的原因的代码的完整版本。请帮助我确定这个小问题。我已尝试使用尽可能多的方法来调试此问题，但无济于事。

这是我的代码:

import Foundation

// Function to calculate the arithmetic mean

func arithmeticMean(array: [Double]) -> Double {
    var total: Double = 0
    for number in array {
        total += number
    }
    return total / Double(array.count)
}

// Function to calculate the standard deviation

func standardDeviation(array: [Double]) -> Double
{
    let length = Double(array.count)
    let avg = array.reduce(0, {$0 + $1}) / length
    let sumOfSquaredAvgDiff = array.map { pow($0 - avg, 2.0)}.reduce(0, {$0 + $1})
    return sqrt(sumOfSquaredAvgDiff / length)
}

// Function to extract some range from an array

func subArray<T>(array: [T], s: Int, e: Int) -> [T] {
    if e > array.count {
        return []
    }
    return Array(array[s..<min(e, array.count)])
}

// Smooth z-score thresholding filter

func ThresholdingAlgo(y: [Double],lag: Int,threshold: Double,influence: Double) -> ([Int],[Double],[Double]) {

    // Create arrays
    var signals   = Array(repeating: 0, count: y.count)
    var filteredY = Array(repeating: 0.0, count: y.count)
    var avgFilter = Array(repeating: 0.0, count: y.count)
    var stdFilter = Array(repeating: 0.0, count: y.count)

    // Initialise variables
    for i in 0...lag-1 {
        signals[i] = 0
        filteredY[i] = y[i]
    }

    // Start filter
    avgFilter[lag-1] = arithmeticMean(array: subArray(array: y, s: 0, e: lag-1))
    stdFilter[lag-1] = standardDeviation(array: subArray(array: y, s: 0, e: lag-1))

    for i in lag...y.count-1 {
        if abs(y[i] - avgFilter[i-1]) > threshold*stdFilter[i-1] {
            if y[i] > avgFilter[i-1] {
                signals[i] = 1      // Positive signal
            } else {
                // Negative signals are turned off for this application
                signals[i] = -1       // Negative signal
            }
            filteredY[i] = influence*y[i] + (1-influence)*filteredY[i-1]
        } else {
            signals[i] = 0          // No signal
            filteredY[i] = y[i]
        }
        // Adjust the filters
        avgFilter[i] = arithmeticMean(array: subArray(array: filteredY, s: i-lag, e: i))
        stdFilter[i] = standardDeviation(array: subArray(array: filteredY, s: i-lag, e: i))
    }
    return (signals,avgFilter,stdFilter)
}


func viewDidLoad()
{

// Demo

let samples = [0.01, -0.02, -0.02, 0.01, -0.01, -0.01, 0.00, 0.10, 0.31,
               -0.10, -0.73, -0.68, 0.21, 1.22, 0.67, -0.59, -1.04, 0.06, 0.42, 0.07,
               0.03, -0.18, 0.11, -0.06, -0.02, 0.16, 0.21, 0.03, -0.68, -0.89, 0.18,
               1.31, 0.66, 0.07, -1.62, -0.16, 0.67, 0.19, -0.42, 0.23, -0.05, -0.01,
               0.03, 0.06, 0.27, 0.15, -0.50, -1.18, 0.11, 1.30, 0.93, 0.16, -1.32,
               -0.10, 0.55, 0.23, -0.03, -0.23, 0.16, -0.04, 0.01, 0.12, 0.35, -0.38,
               -1.11, 0.07, 1.46, 0.61, -0.68, -1.16, 0.29, 0.54, -0.05, 0.02, -0.01,
               0.12, 0.23, 0.29, -0.75, -0.95, 0.11, 1.51, 0.70, -0.30, -1.48, 0.13,
               0.50, 0.18, -0.06, -0.01, -0.02, 0.03, -0.02, 0.06, 0.03, 0.03, 0.02,
               -0.01, 0.01, 0.02, 0.01]

// Run filter

let (signals,avgFilter,stdFilter) = ThresholdingAlgo(y: samples, lag: 10, threshold: 3, influence: 0.2)

// Print output to console
print("\nOutput: \n ")

    for i in 0...signals.count - 1
    {
        print("Data point \(i)\t\t sample: \(samples[i]) \t signal: \(signals[i])\n")
    }

    // Raw data for creating a plot in Excel
    print("\n \n Raw data for creating a plot in Excel: \n ")
    for i in 0...signals.count - 1
    {
        print("\(i+1)\t\(samples[i])\t\(signals[i])\t\(avgFilter[i])\t\(stdFilter[i])\n")
    }
}

非常感谢您的帮助!我已经添加了整个代码，因此这可能有助于调试问题。

Answer 1

好吧，也许我发现了你的问题。函数 viewDidLoad 不在任何类中，它不会覆盖任何委托(delegate)方法。这意味着它不会在 View 出现时自动调用。

例子

class ViewController: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad() // the view did load gets called when view appears
    // Do any additional setup after loading the view, typically from a nib.
}
}

在这种情况下，我们的类在显示 View 时加载，但您的函数 viewDidLoad 不在任何类中。