假设我有一个数组:
var intArray: [Int] = [1,2,3,4,5] {
didSet{
//print index of value that was modified
}
}
如果我做intArray[2] = 10
,我可以在didSet
里面写什么来打印修改后的值(在本例中为 2)的索引?
zip() 函数对此可能很有用:
class A
{
var array = [1,2,3,4,5]
{
didSet
{
let changedIndexes = zip(array, oldValue).map{$0 != $1}.enumerated().filter{$1}.map{$0.0}
print("Changed indexes: (changedIndexes)")
}
}
}
let a = A()
a.array = [1,2,7,7,5]
// prints: Changed indexes: [2, 3]
它也适用于单个元素更改,但数组会受到多次更改的影响,因此获取更改索引的数组更安全。