iOS macOS NSArray,NSMutableArray, NSDictionary, NSMutableDictionary,增加，删除，修改，查找取值，基本操作

不可修改的数组对象 NSArray

创建方法：@[array]

初始化

//初始化
    NSArray *array = [NSArray arrayWithObjects:@"A",@"B",@"C",@"D",@"E",@"F", nil];
    NSArray *array1 = @[@"a",@"b",@"c",@"d"];
    NSArray *array2 = [[NSArray alloc]init];//一般不会这样用，显得太傻
    NSArray *array3 = @[];//一般要设置为空的数组也不会这样

一般NSArray就是赋值和读取而已，还有清空。

读取NSArray的值

//获取数组元素个数
    NSLog(@"%lu",(unsigned long)array.count);//6
    //获取数组最后一个元素
    NSLog(@"%@",[array lastObject]);//F
    //获取数组第一个元素
    NSLog(@"%@",[array firstObject]);//A
    //获取对象C在数组的位置
    NSLog(@"%lu",(unsigned long)[array indexOfObject:@"C"]);//  2
     //获取数组中索引为2的对象
    NSLog(@"%@",[array objectAtIndex:2]);//C

遍历读取

  //常规老方法
   for (int i = 0 ; i< array.count; i++) {
        NSLog(@"遍历-%@",array[i]);
    }
    
    //增强循坏方法
    for (NSString *str in array) {
        NSLog(@"遍历-%@",str);
    }

   //OC迭代器读取
    [array enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        NSLog(@"遍历-%@-%lu",obj,(unsigned long)idx);
    }];

NSArray中的所有对象执行方法（我还没搞懂这个啥有啥用）

@interface Student : NSObject
- (void)log;
- (void)logInfo:(NSString *)str;
@end

@implementation Student
- (void)log{
    NSLog(@"打印");
}
- (void)logInfo:(NSString *)str{
    NSLog(@"打印-%@",str);
}
@end

---------------------
NSArray *array3 = @[[Student new],[Student new],[Student new],[Student new]];
[array3 makeObjectsPerformSelector:@selector(log)];
[array3 makeObjectsPerformSelector:@selector(logInfo:) withObject:@"p"];

NSArray排序（应该没什么大用）

 NSArray *arr = @[@"90",@"20",@"30",@"10",@"50",];
    //数组中的元素不可以是自定义的
    NSArray *arr1 = [arr sortedArrayUsingSelector:@selector(compare:)];
    NSLog(@"%@",arr1);
    /*
     10,20,30,50,90
     */

    //NSSortStable:串行排序   NSSortConcurrent:并发排序
    NSArray *arr2 = [arr sortedArrayWithOptions:NSSortStable usingComparator:^NSComparisonResult(NSString *obj1, NSString *obj2) {
        //每次调用
        NSLog(@"ob1--%@,obj2--%@",obj1,obj2);
        return [obj1 intValue] < [obj2 intValue];
    }];
    NSLog(@"%@",arr2);
     /*
     90,50,30,20,10
     */

NSArray和NSString转换（这个很有用，非常有用！）

 NSArray *arr = @[@"A",@"B",@"C",@"D"];
    NSString *str = [arr componentsJoinedByString:@"-"];
    NSLog(@"%@",str);//A-B-C-D

    NSString *str1 = @"A-B-C-D";
    NSArray *arr1 = [str1 componentsSeparatedByString:@"-"];
    NSLog(@"%@",arr1);
    /*
     A,B,C,D
     */

NSArray文件读写（这个还可以，少用）

 NSArray *array = [NSArray arrayWithObjects:@"A",@"B",@"C",@"D",@"E",@"F", nil];
    //将数组写入文件，本质是写入一个XML文件，iOS中一般写入plist,不能写入自定义对象
    BOOL flag = [array writeToFile:@"/Users/soso/Desktop/demo1/NSArray/demo.plist" atomically:YES];
    NSLog(@"%d",flag);

    //读文件
    NSArray *arr = [NSArray arrayWithContentsOfFile:@"/Users/soso/Desktop/demo1/NSArray/demo.plist"];
    NSLog(@"%@",arr);//A,B,C,D,E,F

NSArray清空数据（这个经常用！）

[NSArray removeAllObjects];

可修改的数组对象 NSMutableArray

创可变数组removeAllObjects引起崩溃

self.showDataSource =(NSMutableArray *)dataArray;

[self.showDataSource  removeAllObjects];

解决方法：改成这样

self.showDataSource = [[NSMutableArray alloc] initWithArray:dataArray];

创建一个空的数组

 NSMutableArray *arr = [NSMutableArray array];
 NSMutableArray *arr1 = [];

1.可变数组添加元素

 //添加元素
    [arr addObject:@"A"];
    NSLog(@"%@",arr);//A

//插入一个元素
    [arr insertObject:@"D" atIndex:2];
    NSLog(@"%@",arr);// A,B,D,C

//插入多个元素
    NSRange range = NSMakeRange(2, 2);
    NSIndexSet *set = [NSIndexSet indexSetWithIndexesInRange:range];
    [arr insertObjects:@[@"H",@"G"] atIndexes:set];
    NSLog(@"%@",arr);//A,B,H,G,D,C

//将指定数组中的元素都取出来，放到arrM中，拼接数组
    [arr addObjectsFromArray:@[@"B",@"C"]];
    NSLog(@"%@",arr);// A,B,C

2.可变数组删除元素

 //删除
    [arr removeObject:@"B"];//删除其中一个元素
    [arr removeObjectAtIndex:2];//删除指定位置的元素
    [arr removeLastObject];//删除最后一个元素
    [arr removeAllObjects];//清空数组

3.可变数组修改元素

 //替换
    [arr replaceObjectAtIndex:3 withObject:@"L"];
    NSLog(@"%@",arr);//A,B,H,L,D,C

4.可变数组查找读取元素

//常规老方法
   for (int i = 0 ; i< arr.count; i++) {
        NSLog(@"遍历-%@",array[i]);
    }
    
    //增强循坏方法
    for (NSString *str in arr) {
        NSLog(@"遍历-%@",str);
    }

   //OC迭代器读取
    [arr enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        NSLog(@"遍历-%@-%lu",obj,(unsigned long)idx);
    }];

不可修改的字典对象 NSDictionary

创建方法： @{dictionary}

创建一个空的字典

//不要这样初始化，这是一个空的字典不可变字典一般直接赋值使用，常常用于一次性数据的读取，并且不可以做修改

NSDictionary *dict = [NSDictionary dictionary];//不可取

正确的使用

方法一:

NSDictionary *dict = [NSDictionary dictionaryWithObject:@"lnj" forKey:@"name"];
//根据key获取value
NSString *name = [dict objectForKey:@"name"];
NSLog(@"name = %@", name);

方法二:

// 注意: key和value 是一一对应
NSDictionary *dict = [NSDictionary dictionaryWithObjects:@[@"lnj", @"30", @"1.75"] forKeys:@[@"name", @"age", @"height"]];
NSLog(@"%@ %@ %@", [dict objectForKey:@"name"], [dict objectForKey:@"age"], [dict objectForKey:@"height"]);

方法三:

//简写:

NSDictionary *dict = @{key:value};
NSDictionary *dict = @{@"name": @"lnj"};
NSLog(@"%@", dict[@"name"]);

NSDictionary *dict = @{@"name":@"lnj", @"age":@"30", @"height":@"1.75"};
NSLog(@"%@ %@ %@", dict[@"name"], dict[@"age"], dict[@"height"]);

只有读取赋值的信息，和删除字典

1.取值（遍历） 

NSDictionary *dict = @{@"name":@"lnj", @"age":@"30", @"height":@"1.75"};

//获取字典中key和value的个数, 在字典中key称之为键, value称之为值
NSLog(@"count = %lu", [dict count]);

方法一:老式for循环写法

for (int i = 0; i < dict.count; ++i) {
    // 获取字典中所有的key
    NSArray *keys = [dict allKeys];
    // 取出当前位置对应的key
    //        NSLog(@"%@", keys[i]);
    NSString *key = keys[i];
    NSString *value = dict[key];
    NSLog(@"key = %@, value = %@", key, value);
}

方法二:增强for循环写法

// 如何通过forin遍历字典, 会将所有的key赋值给前面的obj
for (NSString *key in dict) {
    //        NSLog(@"%@", key);
    NSString *value = dict[key];
    NSLog(@"key = %@, value = %@", key, value);

}

方法三:OC字典的迭代器来遍历

[dict enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
    NSLog(@"key = %@, value = %@", key, obj);
}];

清空NSDictionary字典

//需要确定你使用的字典是可变的
NSMutableDictionary *dictionary = [@{@"key":@"value"} mutableCopy];
NSLog(@"消空前:\n%@",dictionary);
[dictionary removeAllObjects];
NSLog(@"消空后:\n%@",dictionary);

??附加字典的文件操作

如何对字典文件进行读写?

1.将字典数据写入文件中

NSDictionary *dict = @{@"name":@"lnj", @"age":@"30", @"height":@"1.75"};

[dict writeToFile:@"/Users/xiaomage/Desktop/info.plist" atomically:YES];

2.从文件中读取字典数据

  • 注意: 字典和数组不同, 字典中保存的数据是无序的
  • NSDictionary *newDict = [NSDictionary dictionaryWithContentsOfFile:@"/Users/xiaomage/Desktop/info.plist"];
NSLog(@"%@", newDict);

NSArray *arr = @[@10, @20, @30, @5];
[arr writeToFile:@"/Users/xiaomage/Desktop/abc.plist" atomically:YES];

可修改的字典对象 NSMutableDictionary

NSMutableDictionary *dictM = [NSMutableDictionary dictionary];

1.增加元素

[dictM setObject:@"lnj" forKey:@"name"];
//简写:
dictM[@"name"] = @"lnj";

2.删除元素

[dictM removeObjectForKey:@"name"];
[dictM removeObjectsForKeys:@[@"age", @"height"]];

3.修改元素

  • 利用setObject方法给同名的key赋值, 那么新值会覆盖旧值
  • [dictM setObject:@"88" forKey:@"age"];
//简写:
dictM[@"age"] = @"88";

4.查找取值读取

NSLog(@"name = %@", dictM[@"name"]);
注意??
1.不能使用@{}来创建一个可变的字典
 NSMutableDictionary *dictM = @{@"name":@"lnj"};//编译就会报错
 [dictM setObject:@"30" forKey:@"age"];

2.

  • 如果是不可变字典, 那么key不能相同
  • 如果是不可变字典出现了同名的key, 那么后面的key对应的值不会被保存
  • 如果是在可变数组中, 后面的会覆盖前面的
NSDictionary *dict = @{@"name":@"lmj", @"name":@"lnj"};
NSLog(@"dict = %@", dict);

NSMutableDictionary *dictM = [NSMutableDictionary dictionaryWithObjects:@[@"lmj", @"lnj"] forKeys:@[@"name", @"name"]];
NSLog(@"dict = %@", dictM);
 
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