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4.Foundation框架(四).md

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Foundation框架(四)

NSString

  • 创建
// 第一种创建方式
NSString *s = @"a";

// 第二种方式
NSString *s1 = [NSString new];
s1 = @"b";

// 第三种
for (int i = 0; i<10; i++) {
    NSString *imgName = [NSString stringWithFormat:@"xxxxx%02d.jpg",i];
    // xxxxx00.jpg、xxxxx01.jpg....xxxxx09.jpg
}

// 第四种
NSString *s2 = [[NSString alloc]initWithString:s1];
  • 长度
NSString *str = @"abcd";
NSUInteger len = [str length];
NSLog(@"str length:%ld",len);
  • 字符
unichar ch = [str characterAtIndex:0]
  • 相等
[str1 isEqualToString:str2]
  • 查找某个字符串在另外一个字符串中首次出现的位置
NSString *str1= @"slkioslkgilkdiosflgkhldsiosfndslfdsn";
NSString *str2= @"ios";
NSRange range = [str1 rangeOfString:str2];
NSLog(@"%lu,%lu",range.location,range.length);
  • 类型转换
NSString *str = @"1";
int a = 19;

//把字符串类型转换成其他类型
int b = [str intValue];  //intValue,floatValue,doubleValue
int sum = a+b;

NSMutableArray、NSArray

NSMutableArray和NSArray是OC中使用的数组类，前者是可变数组，后者是不可变数组。

  • NSArray
NSArray *arr = [NSArray arrayWithObjects:@"a", @"b", @"c", nil];
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        NSArray *arr = [NSArray arrayWithObjects:@"a", @"b", @"c", nil];
        NSLog(@"arr = %@", arr);
        NSArray *arr1 = [NSArray arrayWithArray:arr];
        NSLog(@"arr1 = %ld", [arr1 count]);
        NSArray *arr2 = @[@"a", @"b", @"c"];
        NSLog(@"arr2 = %@", arr2);
        
        NSString *str0 = [arr2 objectAtIndex:0];
        NSLog(@"str0 = %@", str0);
        NSString *str = [arr2 lastObject];
        NSLog(@"last str = %@", str);
        NSString *str1 = [arr firstObject];
        NSLog(@"first str = %@", str1);
       if([arr containsObject:@"a"]) {
            NSLog(@"含有此对象");
        }
        
        //数组的遍历
        for (NSInteger i = 0; i < [arr count]; i++) {
            NSLog(@"arr[%ld] = %@",i,arr[i]);
            
        }
        //快速枚举法(快速遍历)
        for (id arr2Q in arr2) {
            NSLog(@"arr2Q = %@",arr2Q);
        }
    }
    return 0;
}

执行结果:

2018-10-09 11:45:04.892806+0800 Hello[2621:36790] arr = (
    a,
    b,
    c
)
2018-10-09 11:45:04.892984+0800 Hello[2621:36790] arr1 = 3
2018-10-09 11:45:04.893036+0800 Hello[2621:36790] arr2 = (
    a,
    b,
    c
)
2018-10-09 11:45:04.893070+0800 Hello[2621:36790] str0 = a
2018-10-09 11:45:04.893103+0800 Hello[2621:36790] last str = c
2018-10-09 11:45:04.893115+0800 Hello[2621:36790] first str = a
2018-10-09 11:45:04.893145+0800 Hello[2621:36790] 含有此对象
2018-10-09 11:45:04.893156+0800 Hello[2621:36790] arr[0] = a
2018-10-09 11:45:04.893168+0800 Hello[2621:36790] arr[1] = b
2018-10-09 11:45:04.893179+0800 Hello[2621:36790] arr[2] = c
2018-10-09 11:45:04.893251+0800 Hello[2621:36790] arr2Q = a
2018-10-09 11:45:04.893284+0800 Hello[2621:36790] arr2Q = b
2018-10-09 11:45:04.893296+0800 Hello[2621:36790] arr2Q = c
  • NSMutableArray
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        NSMutableArray *arr = [[NSMutableArray alloc]init];
        [arr addObject:@"a"];
        NSLog(@"arr = %@",arr);
        [arr addObjectsFromArray:@[@"b",@"D"]];
        NSLog(@"arr = %@",arr);
        [arr insertObject:@"c" atIndex:2];
        NSLog(@"arr = %@",arr);
    
        NSMutableArray  *arr1 = [NSMutableArray arrayWithArray:arr];
        [arr replaceObjectAtIndex:3 withObject:@"d"];
        NSLog(@"arr = %@",arr);
    
        NSString *result = [arr objectAtIndex:0];
        NSLog(@"arr[0] = %@",result);
    
        [arr removeObject:@"d"];
        NSLog(@"arr = %@",arr);
    
        [arr removeObjectAtIndex:2];
        NSLog(@"arr = %@",arr);
    
        [arr removeLastObject];
        NSLog(@"arr = %@",arr);

        [arr removeAllObjects];
        NSLog(@"arr = %@",arr);
    
        [arr1 removeObjectsInArray:@[@"c",@"d"]];
        NSLog(@"arr1 = %@",arr1);
    
        [arr1 exchangeObjectAtIndex:0 withObjectAtIndex:1];
        NSLog(@"arr1 = %@",arr1);
    }
    return 0;
}

执行结果:

2018-10-09 14:17:24.754916+0800 Hello[6931:141861] arr = (
    a
)
2018-10-09 14:17:24.755226+0800 Hello[6931:141861] arr = (
    a,
    b,
    D
)
2018-10-09 14:17:24.755261+0800 Hello[6931:141861] arr = (
    a,
    b,
    c,
    D
)
2018-10-09 14:17:24.755291+0800 Hello[6931:141861] arr = (
    a,
    b,
    c,
    d
)
2018-10-09 14:17:24.755322+0800 Hello[6931:141861] arr[0] = a
2018-10-09 14:17:24.755433+0800 Hello[6931:141861] arr = (
    a,
    b,
    c
)
2018-10-09 14:17:24.755461+0800 Hello[6931:141861] arr = (
    a,
    b
)
2018-10-09 14:17:24.755479+0800 Hello[6931:141861] arr = (
    a
)
2018-10-09 14:17:24.755495+0800 Hello[6931:141861] arr = (
)
2018-10-09 14:17:24.755553+0800 Hello[6931:141861] arr1 = (
    a,
    b,
    D
)
2018-10-09 14:17:24.755570+0800 Hello[6931:141861] arr1 = (
    b,
    a,
    D
)

字典

Java中的map

NSDictionary(不可变数据字典) NSMutableDictionary(可变数据字典)

  • 由键值对(key-value)组成的数据集合
  • 任何对象都可以作键，但一般都是字符串
  • 字典内元素无序排列，键相同的元素不能重复
  • 可以通过键来快速枚举
//1、用一个或多个键值对初始化一个字典对象: 以值,建,值,键,...,nil的顺序
NSDictionary *dict01=[[NSDictionary alloc] initWithObjectsAndKeys:@"key0",@"value0",@"key1",@"value1",@"key2",@"value2", nil];
NSLog(@"dict01:%@",dict01);
NSDictionary *dict1=[NSDictionary dictionaryWithObjectsAndKeys:@123,@"key0",@456,@"key1",@678,@"key2", nil];
NSLog(@"dict1:%@",dict1);
//2、用两个数组初始化一个字典，一个key数组，一个value数组，两个数组大小必须相等，否则Crash
NSArray *keyArray=@[@"name0",@"name1",@"name2"];
NSArray *valueArray=@[@"hong",@"wang",@"zhao"];
NSDictionary *dict02=[[NSDictionary alloc] initWithObjects:keyArray forKeys:valueArray];
NSDictionary *dict2=[NSDictionary dictionaryWithObjects:valueArray forKeys:keyArray];
NSLog(@"dict02:%@",dict02);
NSLog(@"dict2:%@",dict2);

//3、用一个数据字典初始化另一个数据字典
NSDictionary *dict03=[[NSDictionary alloc] initWithDictionary:dict1];
NSDictionary *dict3=[NSDictionary dictionaryWithDictionary:dict1];
NSLog(@"dict03:%@",dict03);
NSLog(@"dict3:%@",dict3);

//1、保存字典对象内容到文件
[dict3 writeToFile:@"/Users/apple/Desktop/tesk.txt" atomically:YES];

//2、从之前保存的文件读取数据到字典对象
NSDictionary *dict4=[NSDictionary dictionaryWithContentsOfFile:@"/Users/apple/Desktop/tesk.txt"];

执行结果:

2018-10-09 14:42:13.099190+0800 Hello[7982:155863] dict01:{
    value0 = key0;
    value1 = key1;
    value2 = key2;
}
2018-10-09 14:42:13.099487+0800 Hello[7982:155863] dict1:{
    key0 = 123;
    key1 = 456;
    key2 = 678;
}
2018-10-09 14:42:13.099544+0800 Hello[7982:155863] dict02:{
    hong = name0;
    wang = name1;
    zhao = name2;
}
2018-10-09 14:42:13.099564+0800 Hello[7982:155863] dict2:{
    name0 = hong;
    name1 = wang;
    name2 = zhao;
}
2018-10-09 14:42:13.099601+0800 Hello[7982:155863] dict03:{
    key0 = 123;
    key1 = 456;
    key2 = 678;
}
2018-10-09 14:42:13.099624+0800 Hello[7982:155863] dict3:{
    key0 = 123;
    key1 = 456;
    key2 = 678;
}
  • 元素获取及遍历
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        NSDictionary *dict1=[NSDictionary dictionaryWithObjectsAndKeys:@123,@"key0",@456,@"key1",@678,@"key2", nil];
        //1、分别获取字典的所有键、值
        NSArray *allkeys=[dict1 allKeys];
        NSLog(@"allkeys:%@",allkeys);
        NSArray *allvalues=[dict1 allValues];
        NSLog(@"allvalues:%@",allvalues);
        
        //2、通过指定的key取对应的value对象,没有这个key的话.返回nil
        NSNumber *num1 = [dict1 objectForKey:@"key1"];
        NSNumber *num2 = [dict1 objectForKey:@"key5"];
        NSLog(@"%@",num1);
        NSLog(@"%@",num2);
        
        //3、获取字典中键值对的个数
        NSUInteger paircount=[dict1 count];
        NSLog(@"%lu",paircount);

        for (id key in dict1) {
            id value=[dict1 objectForKey:key];
            NSLog(@"%@=%@",key,value);
        }
    }
    return 0;
}

执行结果:

2018-10-09 14:47:58.817023+0800 Hello[8191:159050] allkeys:(
    key1,
    key0,
    key2
)
2018-10-09 14:47:58.817297+0800 Hello[8191:159050] allvalues:(
    456,
    123,
    678
)
2018-10-09 14:47:58.817331+0800 Hello[8191:159050] 456
2018-10-09 14:47:58.817343+0800 Hello[8191:159050] (null)
2018-10-09 14:47:58.817353+0800 Hello[8191:159050] 3
2018-10-09 14:47:58.817402+0800 Hello[8191:159050] key1=456
2018-10-09 14:47:58.817427+0800 Hello[8191:159050] key0=123
2018-10-09 14:47:58.817439+0800 Hello[8191:159050] key2=678
  • NSMutableDictionary
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        //可变数据字典初始化
        NSMutableDictionary *mDict1=[NSMutableDictionary dictionaryWithObjectsAndKeys:@"aaa",@"name0",@"bbb",@"name1",@"ccc",@"name2", nil];
        NSLog(@"%@",mDict1);
        
        //1、加入元素到NSMutableDictionary中  （注意：当key值中存在要添加的键值对中的key值时，则添加，否则覆盖）
        [mDict1 setObject:@"ddd" forKey:@"name3"];
        [mDict1 setObject:@"eee" forKey:@"name1"];
        NSLog(@"add:  %@",mDict1);
        
        //2、查看 中所有元素个数：
        NSLog(@"%lu",mDict1.count);
        NSNumber *num3 =[mDict1 objectForKey:@"name1"];
        NSLog(@"%@",num3);
        NSNumber *num4 = [mDict1 objectForKey:@"name10"];
        NSLog(@"%@",num4);
    
        //3、根据key值删除
        [mDict1 removeObjectForKey:@"name1"];
        NSLog(@"---%@",mDict1);
        //4、删除所有
        [mDict1 removeAllObjects];
        NSLog(@"%@",mDict1);
    }
    return 0;
}

运行结果:

2018-10-09 15:16:28.171512+0800 Hello[8960:169380] {
    name0 = aaa;
    name1 = bbb;
    name2 = ccc;
}
2018-10-09 15:16:28.171748+0800 Hello[8960:169380] add:  {
    name0 = aaa;
    name1 = eee;
    name2 = ccc;
    name3 = ddd;
}
2018-10-09 15:16:28.171768+0800 Hello[8960:169380] 4
2018-10-09 15:16:28.171794+0800 Hello[8960:169380] eee
2018-10-09 15:16:28.171805+0800 Hello[8960:169380] (null)
2018-10-09 15:16:28.171825+0800 Hello[8960:169380] ---{
    name0 = aaa;
    name2 = ccc;
    name3 = ddd;
}
2018-10-09 15:16:28.171841+0800 Hello[8960:169380] {
}

NSFileManager

用来操作磁盘上的文件、文件夹，对他们进行创建、删除、赋值、拷贝、移动

这个类是以单例模式创建的，想要得到该类对象，需要通过下面的方式:

NSFileManager *fileManager = [NSFileManager defaultManager];

常用方法:

  • （BOOL)fileExistsAtPath:(NSString *)path;
  • (BOOL)isREadableFileAtPath:(NSString *)path;

NSDate 时间处理

NSDate *date=[NSDate date];
NSLog(@"%@",date);
NSDateFormatter *dateFormatter=[[NSDateFormatter alloc] init];
dateFormatter.dateFormat=@"yyyy年MM月dd日 HH:mm:ss";
NSLog(@"%@",[dateFormatter stringFromDate:date]);