Object-C 语法 字符串 数组 字典 和常用函数 学习笔记

字符串

   //取子字符串
        NSString *str1=@"今天的猪肉真贵,200块一斤";
        
        NSString *sub1=[str1 substringFromIndex:4];
        NSLog(@"%@",sub1);//肉真贵,200块一斤
        
        //区间
        NSRange ran=NSMakeRange(3, 2);
        
        NSString *sub2=[str1 substringWithRange:ran];
        NSLog(@"%@",sub2);//猪肉
        
        //字符串拼接
        NSString *str3=@"进能越塔送人头";
        NSString *str4=@"退可挂机骂队友";
        NSString *newStr=[str3 stringByAppendingString:str4];
        
        NSLog(@"拼接的结果是%@",newStr);
        //字符串替换
        NSString *str5=@"iPhone6";
        NSString *newstr1=[str5 stringByReplacingOccurrencesOfString:@"6" withString:@"7"];
        NSLog(@"%@",newstr1);
        //区间替换
        NSString *newstr2=[str5 stringByReplacingCharactersInRange:NSMakeRange(1, 2) withString:@"66"];
        NSLog(@"%@",newstr2);
        
        
        //大小写
        NSString *str6=@"diaozhatian";
        NSString *newstr3=[str6 uppercaseString];
        NSLog(@"%@",newstr3);
         newstr3=[newstr3 lowercaseString];
        NSLog(@"%@",newstr3);
        
        //判断开头和结尾
        NSString *webStr=@"www.jizhousoft.com";
        //判断开头
        BOOL r1=[webStr hasPrefix:@"www"];
        NSLog(@"%d",r1);//1
        //判断结尾
        BOOL r2=[webStr hasSuffix:@"com"];
        NSLog(@"%d",r2);//1
        
        //是否包含
        NSString *str7=@"我赵日天服了!";
        BOOL r3=[str7 containsString:@"日"];
        if (r3) {
            NSLog(@"请文明聊天.");
            NSString *new3=[str7 stringByReplacingOccurrencesOfString:@"日" withString:@"*"];
            NSLog(@"%@",new3);
        }else {
            NSLog(@"真乖!");
        }
//可变字符串 相当于  C#的 StringBuilder
        NSMutableString *mStr=[NSMutableString string];
        //初始化为空
//        NSMutableString *mStr1=[[NSMutableString alloc] initWithCapacity:1];
        [mStr appendString:@"1111"];
        [mStr appendString:@"2222"];
        [mStr insertString:@"666" atIndex:3];
             NSLog(@"%@",mStr);
        [mStr deleteCharactersInRange:NSMakeRange(3, 3)];
        
        NSLog(@"%@",mStr);

数组

  //不可变数组
        NSArray *arr1=[NSArray arrayWithObjects:@"孙悟空",@"八戒",@"和尚",@"小白龙", nil];
        //字面量
        NSArray *arr2=@[@"孙悟空",@"八戒",@"和尚",@"小白龙"];
        //数组长度
        NSInteger count=[arr1 count];
        NSLog(@"%ld",count);
        
        NSLog(@"%ld",[arr2 count]);
        //数组中获取元素
        NSString *str=[arr2 objectAtIndex:2];
        NSLog(@"%@",str);
        //第一个 最后一个
        str=[arr2 firstObject];
        NSLog(@"%@",str);
        str=[arr2 lastObject];
        NSLog(@"%@",str);
        NSInteger indexof=[arr2 indexOfObject:@"小白龙"];
        NSLog(@"%ld",indexof);
        
        //是否包含
        BOOL r1=[arr1 containsObject:@"小白龙"];
        NSLog(@"%d",r1);//1
        
        //字符串分割成数组
        NSString *str2=@"我勒,个,去";
        NSArray *arr3=[str2 componentsSeparatedByString:@","];
        NSLog(@"%@",arr3);
        
        //数组拼接成字符串
        NSArray *arr4=@[@"123",@"456",@"789",@"147"];
//        NSArray *arr4=[NSArray arrayWithObjects:  @"123",@"456",@"789",@"147",nil];
        
        NSLog(@"%@",[arr4 componentsJoinedByString:
                     @""]);
        
        
        //可变数组
        NSMutableArray *mArr=[NSMutableArray array];
        
        [mArr insertObject:@"张三" atIndex:0];
        [mArr addObject:@"林黛玉"];
        [mArr addObject:@"李四"];
        for (int i=0; i<[mArr count]; i++) {
            NSLog(@"%@",[mArr objectAtIndex:i]);
        }
        
//        [mArr removeObjectAtIndex:0];
//        [mArr removeObject:@"林黛玉"];
//        for (int i=0; i<[mArr count]; i++) {
//            NSLog(@"%@",[mArr objectAtIndex:i]);
//        }
        //数组换位
        [mArr exchangeObjectAtIndex:0 withObjectAtIndex:1];
        //替换
        [mArr replaceObjectAtIndex:0 withObject:@"王五"];
        for (int i=0; i<[mArr count]; i++) {
            NSLog(@"%@",[mArr objectAtIndex:i]);
        }

 字典

int main(int argc, const char * argv[]) {
    // insert code here...
    //不可变字典
    NSDictionary *dic=[NSDictionary dictionaryWithObjectsAndKeys:
                       @"哈士奇",@"h",
                       @"柯基",@"k",
                       @"金毛",@"j",
                       nil];
    NSDictionary *dic1=@{@"哈士奇":@"h",
                         @"柯基":@"k",
                         @"金毛":@"j"};
    //获取字典中的元素
    NSString *str=[dic1 objectForKey:@"k"];
    //统计个数
    NSLog(@"%ld",[dic count]);
    
    //获取所有key
    NSArray *arr=[dic1 allKeys];
    
    //获取所有Value
    NSArray *arrValue=[dic allValues];
    
    //可变字典
    
    NSMutableDictionary *mDic=[NSMutableDictionary dictionary];
    [mDic setObject:@"琴女" forKey:@"q"];
    [mDic setObject:@"盲僧" forKey:@"m"];
    [mDic setObject:@"螳螂" forKey:@"t"];
    [mDic setObject:@"淘宝" forKey:@"t"];
    
    //移除t
    [mDic removeObjectForKey:@"t"];
    
    for (NSString *item in [mDic allValues]) {
        NSLog(@"%@",item);
    }
    
    return 0;
}

集合

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
  //不可变集合
    NSSet *set1=[NSSet setWithObjects:@"aa",@"22",@"dd",@"gg", nil];
    //集合没有顺序.只能随机读取 而且会自动去除重复
    NSLog(@"%@",set1);
    //获取集合中的元素
 
     NSLog(@"%@",[set1 anyObject]);//随机元素
    
    //可变集合
    NSMutableSet *mSet=[NSMutableSet set];
    [mSet addObject:@"111"];
    [mSet addObject:@"222"];
    [mSet addObject:@"222"];
    [mSet addObject:@"333"];
    [mSet addObject:@"55"];
    NSLog(@"%ld",[mSet count]);//4 去除了重复
    //移除
    [mSet removeObject:@"111"];
    NSLog(@"%ld",[mSet count]);
    
    //计数集合
    NSCountedSet *cSet=[NSCountedSet set];
    [cSet addObject:@"222"];
    [cSet addObject:@"222"];
    [cSet addObject:@"333"];
    [cSet addObject:@"333"];
    [cSet addObject:@"222"];
    [cSet addObject:@"111"];
    [cSet addObject:@"222"];
    NSLog(@"%ld",[cSet countForObject:@"222"]);//4 统计了次数
    
    NSLog(@"%ld",[cSet count]);//3 依然去除了重复
    
    int a=10;
    int b=12;
    //将基本数据类型存入数组
     //先转换为引用类型 字符串
    NSString *astr=[NSString stringWithFormat:@"%d",a];
    NSString *bstr=[NSString stringWithFormat:@"%d",b];
   //再存入数组中
    NSArray *array=[NSArray arrayWithObjects:astr,bstr, nil];
    
    //或者转换为 NSNumber
    float f1=9.44;
    NSNumber *n1=[NSNumber numberWithFloat:f1];
    //存入数组
    NSArray *array1=@[n1];
    //从数组中取出
    NSNumber *resultNumber=array1[0];
    //读取时转换
    float resultFloat=[resultNumber floatValue];
    NSLog(@"%f",resultFloat);
    
    
    return 0;
}

视频学习地址: https://ke.qq.com/webcourse/index.html#course_id=169598&term_id=100198033&taid=833404044220030&vid=e14148936nh