如何检查NSMutableArray元素是NSNull还是AnyObject [英] how to check if NSMutableArray element is NSNull or AnyObject
问题描述
我有一个 PersonsArray:NSMutableArray = [NSNull,NSNull,NSNUll,NSNull,NSNull,NSNUll,NSNull]
。我需要七个插槽,然后可以将它们作为Entity CoreData条目填充为AnyObject。
I have a PersonsArray: NSMutableArray = [NSNull, NSNull, NSNUll, NSNull, NSNull, NSNUll, NSNull]
. I needed seven slots that I then can fill with an Entity CoreData entry as AnyObject.
我需要在此NSMutableArray上进行for in循环...
I need to do a for in loop on this NSMutableArray...
如果索引槽是NSNull,我想传递到下一个索引槽,如果索引槽中充满了我的对象,我想在该对象上执行代码。
If the index slot is NSNull I want to pass to next index slot, if index slot is filled with my Object I want to execute code on this Object.
example PersonsArray: NSMutableArray = [
NSNull,
NSNull,
NSNull,
"<iswift.Person: 0x7f93d95d6ce0> (entity: Person; id: 0xd000000000080000 <x-coredata://8DD0B78C-C624-4808-9231-1CB419EF8B50/Person/p2> ; data: {\n image = nil;\n name = dustin;\n})",
NSNull,
NSNull,
NSNull
]
尝试
for index in 0..<PersonsArray.count {
if PersonsArray[index] != NSNull {println(index)}
}
建议一堆也不起作用的更改,例如
suggests a bunch of changes that don't work either, like
if PersonsArray[index] as! NSNull != NSNull.self {println(index)}
或
if PersonsArray[index] as! NSNull != NSNull() {println(index)}
注意:使用NSNull只是NSMutableArray中的占位符,因此其计数始终为7,我可以用Object替换任何(7)插槽。我应该使用NSNull以外的其他东西作为占位符吗?
NOTE: using NSNull is just a placeholder in NSMutableArray so that its count is ALWAYS 7 and I can replace any of the (7)slots with an Object. Should I be using something other than NSNull as my placeholder?
推荐答案
NSNull()
是一个单例对象,因此您可以简单地测试数组元素
是否为 NSNull
的实例:
NSNull()
is a singleton object, therefore you can simply test if
the array element is an instance of NSNull
:
if personsArray[index] is NSNull { ... }
或使用 identical to运算符:
or use the "identical to" operator:
if personsArray[index] === NSNull() { ... }
或者,您可以使用一系列可选项:
Alternatively, you could use an array of optionals:
let personsArray = [Person?](count: 7, repeatedValue: nil)
// or more verbosely:
let personsArray : [Person?] = [ nil, nil, nil, nil, nil, nil, nil ]
nil
表示空插槽。
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