How to beat NSMutableArray performance with Swift (beta) Array?

Question

In Swift, I'm trying to build a large collection of items. When creating elements in CoreData on-the-go, this is very speedy. However when trying to keep an index to those items, creating an array Swift has a large performance impact. The code below is a benchmark between NSMutableArray and Swift's Array. When ran in the iOS Simulator, the Swift Array is around 8x slower. Why is this, can it be improved, or should it improve over the as Apple releases new builds of Xcode/Swift? Code: ``` var start: NSDate var time: NSTimeInterval var batch = 1000000 var rate: Double var oArr = NSMutableArray(capacity: batch) start = NSDate() for i in 1..batch { oArr.addObject(i) } time = -start.timeIntervalSinceNow rate = Double(batch) / Double(time) println("NSMutableArray \(batch) appends in \(time) sec: \(rate)/sec") var sArr = Int[]() start = NSDate() for i in 1..batch { sArr += i } time = -start.timeIntervalSinceNow rate = Double(batch) / Double(time) println("Array<Int> \(batch) appends in \(tim…

Accepted Answer

Update: with Xcode beta-3, with a console program on a MacBook Pro 2 GHz Intel Core i7, I get these numbers with the original test (also fixed syntax due to minor grammar changes): Debug (-O0): ``` NSMutableArray 1000000 appends in 0.782136023044586 sec: 1278549.9843203/sec Array 1000000 appends in 5.56463801860809 sec: 179706.208500177/sec ``` Release (-Os): ``` NSMutableArray 1000000 appends in 0.14977502822876 sec: 6676680.43081684/sec Array 1000000 appends in 0.124498963356018 sec: 8032195.3937913/sec ``` Release (-Ofast): ``` NSMutableArray 1000000 appends in 0.151567995548248 sec: 6597698.91646863/sec Array 1000000 appends in 0.122538030147552 sec: 8160731.80543105/sec ```

How to beat NSMutableArray performance with Swift (beta) Array?

Solution

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