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[英]How to save objects indexes inside an array and then display if the position of index has changed when the array gets updated
[英]Property Observer for Array, that gets the changed index
我有一個Array
:
let myArray = [String]()
我想添加一個didSet { }
,它知道實際更改的數組索引。
你可以試試這個-
let myArray = [String]()
class YourClassName
{
var array = [1,2,3,4,5]
{
didSet
{
let changedIndexes = zip(array, myArray).map{$0 != $1}.enumerated().filter{$1}.map{$0.0}
print("Changed indexes: \(changedIndexes)")
}
}
}
let demo = YourClassName()
demo.array = [1,2,7,7,5]
// prints: Changed indexes: [2, 3]
這將為您提供所有已更改的索引,即使數組的長度不同:
class TestClass {
var array: [String] = ["a", "2", "3", "d", "5", "has one more"] {
didSet {
var changed = zip(array, oldValue).enumerated().reduce([]) { $1.element.0 == $1.element.1 ? $0 : $0 + [$1.offset] }
changed.append(Array(min(array.count, oldValue.count)..<max(array.count, oldValue.count)))
print(changed) // prints: [0, 3, 5]
}
}
}
TestClass().array = ["1", "2", "3", "4", "5"]
第一行:
var changed = zip(array, oldValue).enumerated().reduce([]) { $1.element.0 == $1.element.1 ? $0 : $0 + [$1.offset] }
獲取所有不同的索引,直到最短數組的末尾,第二行:
changed.append(Array(min(array.count, oldValue.count)..<max(array.count, oldValue.count)))
追加較長數組的其余索引。
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