在swift中将数组的一个子集设置为相同的值[重复]

Question

Swift 5、iOS 13

我得到了这个代码......这太糟糕了。

var horizonalOpacity = [Bool](repeating: false, count: 24)

self.horizonalOpacity[0] = true
self.horizonalOpacity[1] = true
self.horizonalOpacity[2] = true
self.horizonalOpacity[3] = true
self.horizonalOpacity[4] = true
self.horizonalOpacity[5] = true
self.horizonalOpacity[6] = true
self.horizonalOpacity[7] = true
self.horizonalOpacity[8] = true
self.horizonalOpacity[9] = true
self.horizonalOpacity[10] = true
self.horizonalOpacity[11] = true

我可以用这个代码替换，没关系。

for loop in 0...11 {
   self.horizonalOpacity[loop] = true
}

但是我可以做得更好吗？我可以使用地图吗？或者一个数组切片？

Answer 1

怎么样

var horizonalOpacity = [Bool](repeating: true, count: 12) + 
                       [Bool](repeating: false, count: 12)

Answer 2

你也可以尝试使用mapInPlace扩展建议here：

extension MutableCollection {
    mutating func mapInPlace(_ x: (inout Element) -> ()) {
        for i in indices {
            x(&self[i])
        }
    }
}

那你就写：

horizonalOpacity.mapInPlace { $0 = true }