Swift 4.0+ 数组遍历

1、转换成OC数组 enumerated函数遍历

(keyArr as NSArray).enumerateObjects({ (obj, idx, stop) in
     if (obj as! String).elementsEqual(str) {
         a = true
     }
})

2、用enumerated()函数遍历

for (index, value) in array.enumerated() {
    print("idx:\(index) value:\(value)")
}

3、下标遍历

let arr: [String] = ["q", "w", "e", "r",  "t", "y"]
   for i in 0..<arr.count {
      let item = arr[i]
      print("\(item)")
   }

4、遍历数组中对象

let arr: [String] = ["q", "w", "e", "r",  "t", "y"]
for (i, item) in arr.enumerated() {
    print("arr[\(i)] = \(item)")
}

5、反序遍历

for i in (0..<10).reversed() {
    print(i)
}
// 这里的打印结果将是 9 8 7 6 5 4 3 2 1 0