Swift3.0学习--数组和字典

数组

定义

1 2	let array = ["小明","中花","大杨"] //不可变 var arrayM = ["小","中","大"] //可变

遍历

下标遍历

for i in 0..<array.count {
 print(array[i]) //输出：小明            
                 //     中花	
                 //     大杨
}

直接内容遍历

for s in array {
    print(s) //输出：小明
             //     中花
             //     大杨
 }

enum block遍历下标和内容

for e in array.enumerated() {
   print("\(e.offset) \(e.element)") //输出：0 小明
							      //     1 中花
							      //     2 大杨
}

遍历下标和内容方式二

for(n, s) in array.enumerated() {
           print("\(n) \(s)")  //输出：0 小明
	     			//     1 中花
		  			//     2 大杨
   }

反序

for s in array.reversed() {
          print(s) //输出：大杨
	  			//     中花
	  			//     小明
  }

反序索引和内容

//错的
  for (n, s) in array.reversed().enumerated() {
       print("\(n) \(s)")  //输出：0 大杨
	 			//     1 中花
	 			//     2 小明
   }
   //对的
   for (n, s) in array.enumerated().reversed() {
       print("\(n) \(s)") //输出：2 大杨
       			//	 1 中花
			   //	 0 小明
   }

增

1
2
3

var arrayM = ["小","中","大"] //可变
arrayM.append("超大")
print(arrayM); //输出: ["小", "中", "大", "超大"]

var arrayM = ["小","中","大"] //可变
arrayM.remove(at: 1)
print(arrayM); //输出: ["小", "大", "超大"]
arrayM.removeAll(keepingCapacity: true) //删除数据保持容量
print("\(arrayM) 容量\(arrayM.capacity)") //输出: [] 容量6

1
2
3

var arrayM = ["小","中","大"] //可变
arrayM[1] = "很小" 
print(arrayM); //输出:["小", "很小", "超大"]

合并

let array = ["小明","中花","大杨"] //不可变
var arrayM = ["小","中","大"] //可变
let arr = array + arrayM
print(arr) //输出:["小明", "中花", "大杨", "小", "中", "大"]

容量

数组的容量是个重要的属性,初始化的时候分配capacity,可以提高效率

  var arr = [Int]() //初始化没有分配capacity
        for i in 0...8{
            arr.append(i)
            print("\(arr) 容量\(arr.capacity)")
            }
//输出:可见内存是2倍增长的
[0] 容量2
[0, 1] 容量2
[0, 1, 2] 容量4
[0, 1, 2, 3] 容量4
[0, 1, 2, 3, 4] 容量8
[0, 1, 2, 3, 4, 5] 容量8
[0, 1, 2, 3, 4, 5, 6] 容量8
[0, 1, 2, 3, 4, 5, 6, 7] 容量8
[0, 1, 2, 3, 4, 5, 6, 7, 8] 容量16

字典

定义

//定义普通字典
let dict = ["name" : "Wang", "age" : 18] as [String : Any]//不可变
print(dict)  //输出:["name": "Wang", "age": 18]
var dict = ["name" : "Wang", "age" : 18, "sex":"男"] as [String : Any]//可变
print(dict) //输出:["name" : "Wang", "age" : 18, "sex":"男"]
//定义包含字典的数组
let array: [[String: Any]] = [
        ["name" : "Wang", "age" : 18] as [String : Any],
        ["name" : "li", "age" : 19] as [String : Any],
        ["name" : "zhao", "age" : 20] as [String : Any]
        ]
        print(array)
        //输出:[["name": "Wang", "age": 18], ["name": "li", "age": 19], ["name": "zhao", "age": 20]]

遍历

var dict1 = ["name" : "Wang", "age" : 18, "sex":"男"] as [String : Any]
var dict2 = ["name" : "li", "height": 180] as [String : Any]
	    
	for e in dict1 {
	    print("\(e.key)\(e.value)") //输出:nameWang
					//    age18
					//    sex男
	}
	    
	for (key,value) in dict1 {
	    print("\(key)\(value)")//输出:nameWang
					//    age18
					//    sex男
}

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3

var dict = ["name" : "Wang", "age" : 18, "sex":"男"] as [String : Any]
dict["height"] = 190
print(dict)  //输出:["name": "Wang", "age": 18, "height": 190, "sex": "男"]

1
2
3

var dict = ["name" : "Wang", "age" : 18, "sex":"男"] as [String : Any]
dict.removeValue(forKey: "name")
print(dict1) //输出:["age": 18, "sex": "男"]

1
2
3

var dict = ["name" : "Wang", "age" : 18, "sex":"男"] as [String : Any]
dict["name"] = "王"
print(dict)  //输出:["name": "王", "age": 18, "sex": "男"]

合并

var dict1 = ["name" : "Wang", "age" : 18, "sex":"男"] as [String : Any]
var dict2 = ["name" : "li", "height": 180] as [String : Any]
        
    for e in dict2 {
        dict1[e.key] = dict2[e.key]
    }
    print(dict1)  //输出:["name": "li", "age": 18, "height": 180, "sex": "男"]

2017-06-06