Objective-C 学习记录6--dictionary

1.NSDictionary 和NSMutableDictionary

NSDictionary dictionaryWithObjectsAndKeys:~,nil

使用键值对创建字典,用nil标志结束

NSDictionary initWithObjectsAndKeys:

使用键值对初始化字典,也用nil来表示结束.

dictionary count  计算其字典的长度.

dictionary keyEunmerator  将key全部存在NSEunmerator中,可以快速枚举其中的key的值.

dictionary objectForKey: key  通过key来查询值.

demo:

    #import <UIKit/UIKit.h>
    #import "MyClass.h"
    int main(int argc, char *argv[])
    {
        NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; 

        //添加我们的测试代码 

        NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys:@"我是值",@"我是key1",@"我是值2",@"我是key2", nil]; 

        //得到词典的数量
        int count = [dictionary count];
        NSLog(@"词典的数量为： %d",count); 

        //得到词典中所有KEY值
        NSEnumerator * enumeratorKey = [dictionary keyEnumerator]; 

        //快速枚举遍历所有KEY的值
        for (NSObject *object in enumeratorKey) {
            NSLog(@"遍历KEY的值: %@",object);
        } 

        //得到词典中所有Value值
         NSEnumerator * enumeratorValue = [dictionary objectEnumerator]; 

        //快速枚举遍历所有Value的值
        for (NSObject *object in enumeratorValue) {
            NSLog(@"遍历Value的值: %@",object);
        } 

        //通过KEY找到value
        NSObject *object = [dictionary objectForKey:@"我是key2"]; 

        if (object != nil) {
            NSLog(@"通过KEY找到的value是: %@",object);
        } 

        int retVal = UIApplicationMain(argc, argv, nil, nil);
        [pool release];
        return retVal;
    } 

2.NSMutableDictionary是NSDictionary的子类,因此也继承其有的方法.

[NSMutableDictionary dictionaryWithCapacity:10];
//创建一个长度为10的字典,不过字典的内容超过了10会自动增加.

[NSMutableDictionary initWithCapacity: ];
//初始化长度为10;

[dictionary setObject:~ forKey;~];
//x向可变的字典中添加数据;

[dictionary removeAllobjects];//删除所有的数据;

removeObjectForKey: //删除key的对应值;

    #import <UIKit/UIKit.h>
    #import "MyClass.h"
    int main(int argc, char *argv[])
    {
        NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; 

        //添加我们的测试代码 

        //创建词典对象，初始化长度为10
        NSMutableDictionary *dictionary = [NSMutableDictionary dictionaryWithCapacity:]; 

        //向词典中动态添加数据
        [dictionary setObject:@"被添加的value1" forKey:@"key1"]; 

        [dictionary setObject:@"被添加的value2" forKey:@"key2"]; 

        //通过KEY找到value
        NSObject *object = [dictionary objectForKey:@"key2"]; 

        if (object != nil) {
            NSLog(@"通过KEY找到的value是: %@",object);
        } 

        int retVal = UIApplicationMain(argc, argv, nil, nil);
        [pool release];
        return retVal;
    } 

 

[NSMutableDictionary dictionaryWithCapacity:10];
//创建一个长度为10的字典,不过字典的内容超过了10会自动增加.