ios - 在 Swift 和 iOS 支持中使用空字符串过滤 NSDictionary >= 8.0

Question

我有一个字典，其中包含某些值是空字符串的方式。

let fbPostDic: [String: AnyObject] = [
    "title":"",
    "first_name”:”Ali“,
    "last_name”:”Ahmad“,
    "nick_name”:”ahmad”,
    "gender":1,
    "gender_visibility":2,
    "dob":"1985-08-25",
    "dob_visibility":2,
    "city":"Lahore",
    "city_visibility":2,
    "bio”:”Its bio detail.”,
    "bio_visibility":2,
    "nationality":"Pakistan",
    "nationality_visibility":2,
    "relationship_status”:”Single”,
    "rel_status_visibility":2,
    "relation_with":"",
    "relation_with_visibility":2,
    "social_media_source":"Facebook",
]

我想过滤这个字典，使新字典只包含没有空字符串的元素。

let fbPostDic: [String: AnyObject] = [
    "first_name”:”Ali“,
    "last_name”:”Ahmad“,
    "nick_name”:”ahmad”,
    "gender":1,
    "gender_visibility":2,
    "dob":"1985-08-25",
    "dob_visibility":2,
    "city":"Lahore",
    "city_visibility":2,
    "bio”:”Its bio detail.”,
    "bio_visibility":2,
    "nationality":"Pakistan",
    "nationality_visibility":2,
    "relationship_status”:”Single”,
    "rel_status_visibility":2,
    "relation_with_visibility":2,
    "social_media_source":"Facebook",
]

目前的方法有

let keysToRemove = dict.keys.array.filter { dict[$0]! == nil }

但支持iOS9.0以上版本。我也想支持iOS8.0。

有什么建议吗？

Answer 1

由于上面的dict是一个常量，在Dictionary extension中增加一个额外的init方法可以简化这个过程:

extension Dictionary where Key: StringLiteralConvertible, Value: AnyObject {
    init(_ elements: [Element]){
        self.init()
        for (key, value) in elements {
            self[key] = value
        }
    }
} 
print(Dictionary(dict.filter { $1 as? String != "" }))

但是，如果上面的dict可以声明为一个变量。可能在没有上面额外的词典扩展的情况下尝试下面的一个:

var dict: [String : AnyObject] = [...]
dict.forEach { if $1 as? String == "" { dict.removeValueForKey($0) } }
print(dict)