Objective-C中NSNumber與NSDictionary的用法簡(jiǎn)介

2020-07-26 03:33:53

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供稿：網(wǎng)友

NSNumber的常用方法

在Objective-c中有int的數(shù)據(jù)類型，那為什么還要使用數(shù)字對(duì)象NSNumber？這是因?yàn)楹芏囝悾ㄈ鏝SArray）都要求使用對(duì)象，而int不是對(duì)象。
NSNumber就是數(shù)字對(duì)象我們可以使用NSNumber對(duì)象來創(chuàng)建和初始化不同類型的數(shù)字對(duì)象。
NSNumber
   + (NSNumber *)numberWithInt:(int)value;
   + (NSNumber *)numberWithDouble:(double)value;
   - (int)intValue;
   - (double)doubleValue;
   .....................(對(duì)于每個(gè)基本類型，類方法都為這它分配了一個(gè)NSNumber對(duì)象，并將其設(shè)置為指定的值，這些方法都是以numberWith開始的，之后是類型，如numberWithFloat,numberWithLong,numberWithInteger.....)
包裝后取出來的方法如下:

下面就拿int做個(gè)demo:

復(fù)制代碼代碼如下:

void number() {  
    // 將int類型的10 包裝成 一個(gè)NSNumber對(duì)象  
    NSNumber *number = [NSNumber numberWithInt:10];  
    NSLog(@"number=%@", number);  
      
    NSMutableArray *array = [NSMutableArray array];  
    // 添加數(shù)值到數(shù)組中  
    [array addObject:number];  
      
    // 取出來還是一個(gè)NSNumber對(duì)象，不支持自動(dòng)解包(也就是不會(huì)自動(dòng)轉(zhuǎn)化為int類型)  
    NSNumber *number1 = [array lastObject];  
      
    // 將NSNumber轉(zhuǎn)化成int類型  
    int num = [number1 intValue];  
    NSLog(@"num=%i", num);  
}  

NSDictionary一些常用用法

復(fù)制代碼代碼如下:

NSArray * skyAArrays = [NSArray arrayWithObjects:@"A天空1號(hào)",@"A天空2號(hào)",@"A天空3號(hào)",nil];
    NSArray * skyBArrays = [NSArray arrayWithObjects:@"B天空1號(hào)",@"B天空2號(hào)",@"B天空3號(hào)",nil];
    NSArray * skyCArrays = [NSArray arrayWithObjects:@"C天空1號(hào)",@"C天空2號(hào)",@"C天空3號(hào)",nil];

    // NSArray * skyArray = [NSArray arrayWithObjects:skyAArrays,skyBArrays,skyCArrays, nil];

   //字典中所有的key
    NSArray * keys = [NSArray arrayWithObjects:@"name",@"sex",@"age",nil];
   //字典中所有跟key對(duì)應(yīng)的value
    NSArray * values = [NSArray arrayWithObjects:@"liuhui",@"男",[NSNumbernumberWithInt:36],nil];
   //創(chuàng)建字典對(duì)象方法1
    NSDictionary * myDic = [[NSDictionary alloc]initWithObjects:values forKeys:keys];
    NSLog(@"my dic = %@",myDic);
   // 創(chuàng)建字典對(duì)象方法2
    NSDictionary * yourDic = [[NSDictionary alloc] initWithObjectsAndKeys:skyAArrays,@"A",skyBArrays,@"B",skyCArrays,@"C",nil];
    NSLog(@"your dic = %@",yourDic);

    NSLog(@"%@",[yourDic objectForKey:@"A"]);
    // - (NSArray *)allKeys; 返回的是 NSArray類型,方便用 objectAtIndex取出一個(gè)個(gè)key
    NSLog(@"%@",[yourDic allKeys]);
    NSLog(@"%@",[yourDic allValues]);

   //添加數(shù)據(jù)(setObject 一般沒有一種key才添加,有同名的key而用這種方法,會(huì)覆蓋掉)，注意：id key 是成對(duì)出現(xiàn)的
    [mutableDictionary setObject:@"good lucky"forKey:@"why"];
    [mutableDictionary setObject:@"bye bye" forKey:@"how"];

   //刪除指定鍵值的數(shù)據(jù)
    [mutableDictionary removeObjectForKey:..];
   //刪除所有數(shù)據(jù)
    [mutableDictionary removeAllObjects];

    //字典的普通遍歷(無序)
    for (int i =0; i < [yourDic count]; i++) {
        NSLog(@"key = value <====> %@ = %@",[[yourDic allKeys] objectAtIndex:i],[yourDic objectForKey:[[yourDic allKeys]objectAtIndex:i]]);
    }

    // 字典的快速遍歷取出來的obj一定是key
    for (id obj in yourDic) {
        NSLog(@"%@",obj);
        id value = [yourDic objectForKey:obj];
        NSLog(@"%@",value);
    }