objective-c与swift字典的简单使用

分类: NSDictionary (NSDictionaryCreation)
在objective-c中字典的简单使用：

   // 建立一个空字典
   + (instancetype)dictionary;

   // 例子
    NSDictionary * dic = [NSDictionary dictionary];

   // 简写形式
    NSDictionary * dic = @{};

   //  建立一个拥有单个键值对字典
   + (instancetype)dictionaryWithObject:(id)object forKey:(id <NSCopying>)key;
    
   //  实例
   NSDictionary * dic = [NSDictionary dictionaryWithObject:@"OC" forKey:@"OCKey"];
   
   //  简写
   NSDictionary * dic = @{@"OC":@"OCKey"};
   
   // 建立一个拥有多个键值对的字典
   + (instancetype)dictionaryWithObjectsAndKeys:(id)firstObject, ... NS_REQUIRES_NIL_TERMINATION;

   //  实例
   NSDictionary * dic = [NSDictionary dictionaryWithObjectsAndKeys:@"OC",@"OCKey",@"张三",@"name", nil];

   // 简写
   NSDictionary * dic = @{@"OC":@"OCKey",@"张三":@"name"};

以上的例子均为不可变字典,数组所储存的键值对的值为对象,键位字符串的标识,字典一旦决定键值对个数不可添加或删除.

根据键也就是Key来取值.

在swift中字典的简单使用：

    // 实例化一个空字典
    NSDictionary();

    // 简写
    var dic:NSDictionary = [:];

    // 建立一个拥有一个键值对的字典
    convenience init(object: AnyObject, forKey key: NSCopying)
    
    // 例子
    var dic:NSDictionary = NSDictionary(object: "OC", forKey: "OCKey");

    // 简写
    var dic:NSDictionary = ["swiftKey":"swift"];

  
    /** 2015,12,22修改 废弃 */  
    convenience init(objectsAndKeys objects: AnyObject...)

    // 建立一个拥有多个键值对的字典
    public convenience init(objects: [AnyObject], forKeys keys: [NSCopying])

    /** 2015,12,22修改 废弃 */    
    var dic = NSDictionary(objectsAndKeys: "OC","OCKey","张三","name")

    // 例子 
    var dic = NSDictionary(objects: ["张三","OC"], forKeys: ["name","OCKey"]);
    // 简写
    var dic = [ "name":"张三","age":"18","id":"1" ];

    // 指定字典中的参数
    var dic:Dictionary = Dictionary<NSString ,Float>();

在swift中与OC还是有些变化首先简写形式由 @{}变化为 [:]其次,在使用swift的便利构造器时,左边是值,而右边是key, 在简写形式中,则变化为左边是key右边是值.