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print("数组字典") //数组:Array var a1: [Int] = [] if a1.isEmpty { print("数组为空") a1 = [1,2,3,4,5] }
//长度计算 print(a1.count)
//添加元素 a1 += [6] a1.append(7) a1.insert(8, at: 0)
print(a1)
//删除 //删除第一个 a1.removeFirst() //删除前几个 a1.removeFirst(2) //删除指定索引的元素 a1.remove(at: 3) //删除最后一个 a1.removeLast() //删除所有 a1.removeAll()
print(a1)
var a2 = ["one","two","three","four"]
//修改指定索引的元素 a2[0] = "ling" a2[1...3] = ["er","san","si"] print(a2) //是否包含元素 print(a2.contains("two")) //遍历数组 for ele in a2 { print(ele) } for (index,value) in a2.enumerated() { print("a2[\(index)] = \(value)") }
//var array: NSArray = [123, 456]
//字典:Dictionary var d1:[Int: String] = [1:"one",2:"two"]
//添加元素 d1[3] = "three" d1.updateValue("four", forKey: 4)
print(d1)
//删除元素 d1.removeValue(forKey: 1) //d1.removeAll() //所有键 for key in d1.keys { print(key) } for value in d1.values { print(value) } //遍历字典 for (key,value) in d1 { print("\(key):\(value)") }
var aaa: NSMutableArray = []
aaa.add("abc") aaa.add(250)
#if true //将获取的元素强制转换为String类型,若能够则转换成功 var bbb: String = aaa[0] as! String #else //若不能转换成功,则会出现崩溃 var bbb: String = aaa[1] as! String #endif print(bbb)
#if false //将获取的元素转换为Int?类型,若能够则转换成功 var ccc: Int? = aaa[1] as? Int #else //若不能转换成功,则返回nil var ccc: Int? = aaa[0] as? Int
#endif print(ccc)
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