ios - 计算属性 getter 出错

Question

我在 iOS Swift 3 应用程序中有以下计算属性。

var countItems:[Int] {// Count the interesting items.
    var countResult = [Int]()
    for i in 0..<size {
        var count = 0
        for j in i*size..<(i+1)*size {
            if binaryArray?[j] == true {count += 1}
        }
        countResult.append(count)
    }
    return countResult
}

它在 99.9% 的时间里都能完美运行。但是这条消息让我崩溃了:

* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=2, address=0x16fc7bff0)
    frame #0: 0x000000018f2d95b8 libsystem_malloc.dylib`malloc_zone_malloc
    frame #1: 0x000000018f2dc56c libsystem_malloc.dylib`malloc + 32
    frame #2: 0x0000000100964048 libswiftCore.dylib`swift_slowAlloc + 12
    frame #3: 0x000000010096409c libswiftCore.dylib`_swift_allocObject_ + 28
    frame #4: 0x0000000100f6cd50 libswiftSwiftOnoneSupport.dylib`generic specialization <preserving fragile attribute, Swift._ArrayBuffer<Swift.Double> with Swift._ArrayBuffer<Swift.Double> : Swift._ArrayBufferProtocol in Swift> of (extension in Swift):Swift._ArrayBufferProtocol._forceCreateUniqueMutableBuffer (countForNewBuffer : Swift.Int, minNewCapacity : Swift.Int) -> Swift._ContiguousArrayBuffer<A.Element> with unmangled suffix "_merged" + 84
    frame #5: 0x0000000100f69d5c libswiftSwiftOnoneSupport.dylib`generic specialization <preserving fragile attribute, Swift.String.CharacterView> of Swift.Array._copyToNewBuffer (oldCount : Swift.Int) -> () with unmangled suffix "_merged" + 76
    frame #6: 0x0000000100f655bc libswiftSwiftOnoneSupport.dylib`generic specialization <preserving fragile attribute, Swift.UInt64> of Swift.Array.append (A) -> () with unmangled suffix "_merged" + 124
  * frame #7: 0x0000000100103078 MyApp`TheClass.countItems.getter(self=MyApp.TheClass @ 0x000000016fc7c260) at TheClass.swift:31
    frame #8: 0x0000000100138354 MyApp`TheClass.callingFunction(self=0x000000010201d930) -> Bool at TheClass.swift:2343

我想知道计算属性本身是否存在问题(我没有看到)或者是否一定是外部出了问题。如果有人有线索，我会很高兴。在此先感谢您提供任何相关提示。

作为引用，这是另一个带有较短消息的崩溃:

(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=2, address=0x16fc27fb0)
    frame #0: 0x00000001001567bc MyApp`TheClass.countItems.getter(self=MyApp.TheClass @ 0x000000016fc27fb0) at TheClass.swift:0
  * frame #1: 0x000000010018c2e4 MyApp`TheClass.callingFunction(self=0x000000010200c730) -> Bool at TheClass.swift:2348

Answer 1

请尝试在后台线程中工作，因为您似乎在主线程中进行所有数字处理，这并不好。

要么你可以创建一个返回整数项数组的函数。它将在后台线程中处理数组。

因为我不知道什么是 binaryArray 变量。如果需要，可以传入。

SWIFT 3.0:

func countItems(_ size : Int, completion: ([Int])) {
    let queue = DispatchQueue.global(qos: .background)
    queue.async {
        var countResult = [Int]()
        for i in 0..<size {
            var count = 0
            for j in i*size..<(i+1)*size {
                if self.binaryArray?[j] == true {count += 1}
            }
            countResult.append(count)
        }
        completion(countResult) 
    }
}