iOS Swift Multiple Dimension Arrays - Compiliing Takes Ages. What Should I Change

Swift Array of Ranges causing issues

Declare your variable as an array of arrays of Int

let arrayOfRanges: [[Int]] = [Array(0 ... 299), Array(300 ... 399), Array(400 ... 699), Array(700 ... 799), Array(800 ... 899), Array(900 ... 1199)]
let magicNumber = arrayOfRanges[2][11]

xy array in Swift performance

I checked the performance for various solutions to your problem. You can download my tests from this link to github

A) Your code

var spectrum: [XYPoint] = []
for i in 0..<xArray.count {
    let xy = XYPoint(x: xArray[i], y: yArray[i])
    spectrum.append(xy)
}

B) Zip + map (Martin R's answer)

let spectrumB = zip(xArray, yArray).map(XYPoint.init)

C) Range + map (My solution)

let spectrum = (0 ..< xArray.count).map { i in
    return XYPoint(x: xArray[i], y: yArray[i])
}

D) ReserveCapacity + append (Duncan C's answer)

var spectrum: [XYPoint] = []
spectrum.reserveCapacity(xArray.count)
for (index, value) in xArray.enumerated() {
    spectrum.append(XYPoint(x: xArray[index], y: yArray[index]))
}

---

My results (in seconds)

            ╭──────────────┬──────────────┬──────────────┬──────────────╮
            │       A      │       B      │       C      │       D      │
╭───────────╬══════════════╪══════════════╪══════════════╪══════════════╡
│       100 ║  0.000009426 │  0.000002401 │  0.000000571 │  0.000000550 │
│       200 ║  0.000003356 │  0.000002629 │  0.000000911 │  0.000000866 │
│       500 ║  0.000005610 │  0.000007288 │  0.000002236 │  0.000002012 │
│      1000 ║  0.000010638 │  0.000009181 │  0.000003905 │  0.000005030 │
│      2000 ║  0.000019377 │  0.000013316 │  0.000007116 │  0.000008732 │
│      5000 ║  0.000023430 │  0.000019304 │  0.000019809 │  0.000019092 │
│     10000 ║  0.000050463 │  0.000031669 │  0.000035121 │  0.000035420 │
│     20000 ║  0.000087040 │  0.000058664 │  0.000069300 │  0.000069456 │
│     50000 ║  0.000272357 │  0.000204213 │  0.000176962 │  0.000192996 │
│    100000 ║  0.000721436 │  0.000459551 │  0.000415024 │  0.000437604 │
│    200000 ║  0.001114534 │  0.000924621 │  0.000816374 │  0.000896202 │
│    500000 ║  0.002576687 │  0.002094998 │  0.001860833 │  0.002060462 │
│   1000000 ║  0.007063596 │  0.005924892 │  0.004319181 │  0.004869024 │
│   2000000 ║  0.014474969 │  0.013594134 │  0.008568550 │  0.009388957 │
│   5000000 ║  0.038348767 │  0.035136008 │  0.021276415 │  0.023855382 │
│  10000000 ║  0.081750925 │  0.078742713 │  0.043578664 │  0.047700495 │
│  20000000 ║  0.202616669 │  0.199960563 │  0.148141266 │  0.145360923 │
│  50000000 ║  0.567078563 │  0.552158644 │  0.370327555 │  0.397115294 │
│ 100000000 ║  1.136993625 │  1.101725386 │  0.713406642 │  0.740150322 │
└───────────╨──────────────┴──────────────┴──────────────┴──────────────┘

Compiling large array literal in Xcode 8.2

I'm sorry to keep making the same joke, but you need to do this the same way Superman gets into his pants: one leg at a time. Start with the overall structure. Then keep making the innermost arrays and appending them into the outer arrays to build up the outermost array. This will get you started:

var level1 : [[[[Int]]]] = []
var level2 : [[[Int]]] = []
var level3 : [[Int]] = []
// -----
level3 = []
let innermost1 = [1,2,3,4,5,6,7,8,9]
let innermost2 = [11,12,13,14,15,16,17,18,19]
level3.append(innermost1)
level3.append(innermost2)
level2.append(level3)
level1.append(level2)
// ... keep going ...

In this way, we never need any big / deep array literals, and the project will compile easily.

Note too that the type of the array at each level is explicitly declared. This makes Swift a lot happier than having to infer it.

---

Related Topics