iOS - Swift Dictionary 字典

前言

	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。

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]

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"))

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

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")

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)

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

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

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])

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])

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()

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)
				}

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))
			}