iOS

• 来源：http://www.cnblogs.com/QianChia/p/5777434.html#_label6

    public struct Dictionary<Key : Hashable, Value> : CollectionType, DictionaryLiteralConvertible    public class NSDictionary : NSObject, NSCopying, NSMutableCopying, NSSecureCoding, NSFastEnumeration

• 字典用于存储无序的数据元素值，它可以存储任何类型的元素，甚至可以将数组作为字典的元素。

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1、Dictionary 与 NSDictionary 的相互转换

• Dictionary 与 NSDictionary 之间可以直接相互转换。Dictionary 转转成 NSDictionary 时，数组中的各项元素被转换为 AnyObject 类型。NSDictionary 转换成 Dictionary 时，数组中的各项元素也被转换为 AnyObject 类型。

    let dictinoary:[String:String] = ["key1":"value1", "key2":"value"]            // Dictionary 转 NSDictionary                    // Dictionary 转换成 NSDictionary<AnyObject, AnyObject> 型        let nsDictionary1:NSDictionary = dictinoary                // Dictionary 转换成 NSDictionary<AnyObject, AnyObject> 型        let nsDictionary2:NSDictionary = dictinoary as NSDictionary                // NSDictionary 转 Dictionary                    // NSDictionary 转换成 Dictionary<AnyObject, AnyObject> 型        let swiftDictionary1:Dictionary = nsDictionary1 as Dictionary                // NSDictionary 转换成 Dictionary<String, String> 型        let swiftDictionary2:Dictionary = nsDictionary1 as! [String:String]

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2、字典的 创建

    // Dictionary 型字典                    // 创建字典变量，指定数据类型为 Int 型        let dic1 = [String:Int]()                // 创建字典变量，Dictionary<String, Int> 等价于 [String:Int]        let dic2 = Dictionary<String, Int>()                // 创建字典变量，不指定数据类型        let dic3:Dictionary = ["key1":1, "key2":2]                // 创建字典变量，指定数据类型为 Int 型        let dic4:Dictionary<String, Int> = ["key1":1, "key2":2, "key3":3]                // 创建字典变量，不指定数据类型        let dic5 = ["key1":1, "key2":2, "key3":3, "key4":4]                // 创建指定数据类型的字典        let dic6:[String:Int] = ["key1":1, "key2":2, "key3":3, "key4":4]                // 创建指定数据类型的字典        let dic7:[String:AnyObject] = ["key1":1, "key2":2, "key3":"value3", "key4":4]                // NSDictionary 型字典                    let swiftDictionary = ["key1":1, "key2":2, "key3":3, "key4":4]                    let nsdic1:NSDictionary = swiftDictionary        let nsdic2:NSDictionary = swiftDictionary as NSDictionary                    let nsdic3:NSDictionary = NSDictionary(dictionary: swiftDictionary)        let nsdic4:NSDictionary = NSDictionary(dictionary: ["key1":1, "key2":2, "key3":3, "key4":4])                    let nsdic5:NSDictionary = NSDictionary(object: "nsdic5", forKey: "key1")        let nsdic6:NSDictionary = NSDictionary(objects: ["nsdic6", 2], forKeys: ["key1", "key2"])        let nsdic7:NSDictionary = NSDictionary(dictionaryLiteral: ("key1", "nsdic7"),                                                                   ("key2", 2),                                                                   ("key3", 3),                                                                   ("key4", 4))                // 从 文件 创建字符串        let nsdic8:NSDictionary? = NSDictionary(contentsOfFile: NSHomeDirectory() + "/Desktop/test.txt")                    // 从 Url 创建字符串                                    let nsdic9:NSDictionary? = NSDictionary(contentsOfURL: NSURL(fileURLWithPath: NSHomeDirectory() +                                                                                       "/Desktop/test.txt"))

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3、字典元素个数的计算

    // Dictionary 或 NSDictionary 型字典            let dic = ["key1":1, "key2":2, "key3":3, "key4":4]            let num:Int = dic.count

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4、通过 key 找对应的 value

    // Dictionary 型字典                    var dic:Dictionary = ["key1":1, "key2":2, "key3":3, "key4":4]                    // 获取字典中指定 key 对应的值        let value1 = dic["key2"]                    // NSDictionary 型字典        let nsDic:NSDictionary = NSDictionary(dictionary: ["key1":1, "key2":2, "key3":3, "key4":4])                    // 获取字典中指定 key 对应的值        let value2:AnyObject? = nsDic["key2"]                // 获取字典中指定 key 对应的值        let value3:AnyObject? = nsDic.objectForKey("key2")                // 获取字典中指定 key 对应的值，key 的值不存在时返回指定的字符串        let value4 = nsDic.objectsForKeys(["key3", "key4", "key5"], notFoundMarker: "not found")

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5、通过 value 找对应的 key

    // NSDictionary 型字典                    let nsDic:NSDictionary = NSDictionary(dictionary: ["key1":1, "key2":3, "key3":3, "key4":4])                    let keys:AnyObject = nsDic.allKeysForObject(3)

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6、字典中所有 key 的获取

    // Dictionary 型字典                    let dic:Dictionary = ["key1":1, "key2":2, "key3":3, "key4":4]                    let keys1 = dic.keys            // NSDictionary 型字典                    let nsDic:NSDictionary = NSDictionary(dictionary: ["key1":1, "key2":2, "key3":3, "key4":4])                    let keys2 = nsDic.allKeys

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7、字典中所有 value 的获取

    // Dictionary 型字典                    let dic:Dictionary = ["key1":1, "key2":2, "key3":3, "key4":4]                    let values1 = dic.values                // NSDictionary 型字典                    let nsDic:NSDictionary = NSDictionary(dictionary: ["key1":1, "key2":2, "key3":3, "key4":4])                    let values2 = nsDic.allValues

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8、字典键值对的 追加

    // Dictionary 型字典                    var dic:Dictionary = ["key1":1, "key2":2, "key3":3, "key4":4]                    // key 不存在时，追加键值对（key 值为新增的，若 key 值已存在则为修改对应的 value 值）        dic["key5"] = 5                // NSDictionary 型字典                let nsDic:NSMutableDictionary = NSMutableDictionary(dictionary: ["key1":1, "key2":2, "key3":3, "key4":4])                    // key 不存在时，追加键值对（key 值为新增的，若 key 值已存在则为修改对应的 value 值）        nsDic["key5"] = 5                // 向字典末尾追加一个字典        nsDic.addEntriesFromDictionary(["key6":6, "key7":7])

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9、字典键值对的 修改

    // Dictionary 型字典                    var dic:Dictionary = ["key1":1, "key2":2, "key3":3, "key4":4]                    // key 存在时，修改其值        dic["key4"] = 100                // 修改指定的 key 对应的值        dic.updateValue(44, forKey: "key4")                // NSDictionary 型字典                let nsDic:NSMutableDictionary = NSMutableDictionary(dictionary: ["key1":1, "key2":2, "key3":3, "key4":4])                    // key 存在时，修改其值        nsDic["key3"] = 33                // 修改指定的 key 对应的值        nsDic.setObject(100, forKey: "key4")                // 修改整个字典        nsDic.setDictionary(["key6":6, "key7":7])

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10、字典键值对的 删除

    // Dictionary 型字典                    var dic:Dictionary = ["key1":1, "key2":2, "key3":3, "key4":4]                    // 删除指定 key 对应的值        dic.removeValueForKey("key2")                // 删除字典的所有元素        dic.removeAll(keepCapacity: true)                // NSDictionary 型字典                    let nsDic:NSMutableDictionary = NSMutableDictionary(dictionary: ["key1":1, "key2":2, "key3":3, "key4":4])                    // 删除指定 key 对应的值        nsDic.removeObjectForKey("key2")                // 删除指定 key 对应的值        nsDic.removeObjectsForKeys(["key1", "key4"])                // 删除字典的所有元素        nsDic.removeAllObjects()

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11、字典遍历

    // NSDictionary 型字典                let nsDic:NSDictionary = NSDictionary(dictionary: ["key1":1, "key2":2, "key3":3, "key4":4])                    // for...in 循环                            // 遍历出的为 key-value 的元组, key 不需要可以用 _ 替代            for (_, obj) in nsDic {                                print(obj)            }                        // 闭包遍历                            nsDic.enumerateKeysAndObjectsUsingBlock { (key:AnyObject, obj:AnyObject, stop:UnsafeMutablePointer<ObjCBool>) in                             print(obj)            }                        // 迭代器遍历                            // key 迭代器                            let keyEnu:NSEnumerator = nsDic.keyEnumerator()                                    while let key:AnyObject = keyEnu.nextObject() {                                        print(nsDic.objectForKey(key))                }                            // 对象迭代器                            let objEnu:NSEnumerator = nsDic.objectEnumerator()                                    while let obj:AnyObject = objEnu.nextObject() {                                        print(obj)                }

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12、字典排序

    // NSDictionary 型字典                    let nsDic:NSDictionary = NSDictionary(dictionary: ["key1":"value1", "key2":"value2", "key3":"value3", "key4":"value4"])                    // 用闭包排序                            let keys1 = nsDic.keysSortedByValueUsingComparator { (obj1:AnyObject, obj2:AnyObject) -> NSComparisonResult in                               return (obj1 as! String).compare(obj2 as! String)            }                            for key in keys1 {                print(nsDic.objectForKey(key))            }                    // 用指定的方法排序                            let keys2 = nsDic.keysSortedByValueUsingSelector(#selector(NSNumber.compare(_:)))                            for key in keys2 {                print(nsDic.objectForKey(key))            }