OC 数组、字典、集合的遍历方法&数组排序

数组排序

一 、遍历

---

For 循环遍历

   
    #数组遍历

    NSArray *array = @[@"zhang",@"wang",@"li"];
    
    for (int i = 0; i < array.count;i++){
    
        NSLog(@"------%@ \n",array[i]);
  
    }
    
    #字典遍历
   
    NSDictionary *dic = @{@"name":@"tom",
                          
                          @"age":@"18",
                          
                          @"sex":@"male"
                          
                          };
    
    // 通过 key
    NSArray *keys = dic.allKeys;
    
    for(int i = 0; i< keys.count; i++){
    
        NSString *key = keys[i];
        
        NSString *str = [dic objectForKey:key];
        
        NSLog(@"%@",str);
    
    
    }
    
    
    //集合遍历
    
    NSSet *set = [NSSet setWithObjects:@"zhang",@"wang",@"li", nil];
    
    // 取出所有对象,变为数组
    NSArray *temp = set.allObjects;
    
    for (int i = 0; i < temp.count; i++) {
        NSLog(@"%@",temp[i]);
    }
    
    

---

NSEnumerator 枚举器遍历

数组,字典,集合都有一个枚举器方法,返回的是枚举器对象

    #数组枚举
    
    // 定义一个数组
    NSArray *array = @[@"wang",@"li",@"zhang"];
    
    
    // 正向枚举
    
    NSEnumerator *enumerator = [array objectEnumerator];
    
    id objecet;
    
    while (objecet = [enumerator nextObject]) {
        
        NSLog(@"正向枚举%@",objecet);
    }
    
    
    // 反向枚举
    
    
    NSEnumerator *reverse = [array reverseObjectEnumerator];
    
    id result2; //
    
    while (result2 = [reverse nextObject]) {
        
        NSLog(@"反向枚举%@", result2);
    }

    
    
    #字典枚举
    
    
    NSDictionary *dic = @{@"name":@"tom",
                           @"age":@"20",
                           @"sex":@"male"};
    
    NSEnumerator *enumDic = [dic objectEnumerator];
    
    id objecetInDic;
    
    while (objecetInDic = [enumDic nextObject]) {
        NSLog(@"枚举器---%@\n",objecetInDic);
    }
    
    
    
    
    # 集合枚举
    
    
    NSSet *set = [NSSet setWithObjects:@"zhang",@"wang",@"li", nil];
    
    NSEnumerator *enumSet = [set objectEnumerator];
    
    id objectInSet;
    
    while (objectInSet = [enumSet nextObject]) {
        NSLog(@"集合---%@\n",objectInSet);
    }
    
    

    

---

for ..in 遍历

1.对于数组,forin 枚举的是对象;

2,对于字典,forin 枚举的是key;

3,对于集合,forin 枚举的是对象;

---

二、数组排序

方法 一：NSSortDescriptor

    NSArray *arr = @[@"zhang",@"wang",@"lili"];
    
    // 创建排序描述对象 
    // 降序(ascending :NO) 升序(ascending :YES)
    NSSortDescriptor *descriptor = [NSSortDescriptor sortDescriptorWithKey:@"self" ascending:NO];
    
 
    // 调用数组的排序方法    
    NSArray *newArr = [arr sortedArrayUsingDescriptors:@[descriptor]];
    
    
    // 遍历输出
    for (NSString *string in newArr) {
        NSLog(@"-----数组%@",string);
    }

• 建一个 Person 类

Person.h

@interface Person : NSObject


@property (nonatomic, retain) NSString *name;
@property (nonatomic, assign) NSInteger age;
@property (nonatomic, retain) NSString *sex;



-(instancetype)initWithName:(NSString *)name age:(NSInteger)age sex:(NSString *)sex;

/** 声明一个按照姓名升序排序的方法. */
- (NSComparisonResult)compareWithNameUP:(Person *)anotherPerson;

/** 声明一个按照姓名 #降序# 排序的方法. */
- (NSComparisonResult)compareWithNameDown:(Person *)anotherPerson;

/**根据年龄进行 #升序#  排序方法大   */
- (NSComparisonResult)compareWithAgeUP:(Person *)anotherPerson;

Person.m

 #import "Person.h"

 @implementation Person

     /**重新初始化方法 */
     -(instancetype)initWithName:(NSString *)name age:(NSInteger)age sex:(NSString *)sex;{

    self = [super init];
    
    if (self) {
       
        self.name = name;
        
        self.age = age;
        
        self.sex = sex;
    }

    return self;

}



     /** 声明一个按照姓名升序排序的方法. */
     - (NSComparisonResult)compareWithNameUP:(Person *)anotherPerson{

    return [self.name compare:anotherPerson.name];
}


     /** 声明一个按照姓名 #降序# 排序的方法. */
     - (NSComparisonResult)compareWithNameDown:(Person *)anotherPerson{

    return [self.name compare:anotherPerson.name] * -1; // - 1 将升序变为降序
}



    /**根据年龄进行 #升序#  排序方法大   */

    - (NSComparisonResult)compareWithAgeUP:(Person *)anotherPerson{


    if (self.age >anotherPerson.age){
    
        return NSOrderedDescending;
    
    }else if (self.age < anotherPerson.age){
    
        return NSOrderedAscending;
        
    }else{
    
    
        return NSOrderedSame;
    }



}



 

Person 数组对象排序

    Person *per1 = [[Person alloc] initWithName:@"zhangsan" age:20 sex:@"male"];
    
    Person *per2 = [[Person alloc] initWithName:@"xiaoming" age:18 sex:@"male"];
    
    Person *per3 = [[Person alloc] initWithName:@"xiaoxue"  age:22 sex:@"female"];
    
    Person *per4 = [[Person alloc] initWithName:@"xiaoli"   age:17 sex:@"female"];
    
    Person *per5 = [[Person alloc] initWithName:@"tom"      age:18 sex:@"female"];
    
    
    NSArray *arr2 = @[per1, per2, per3, per4, per5];// 数组类型
    
    //需求:按照年龄升序排序,如果年龄相同,再按照姓名升序排序
    NSSortDescriptor *name = [NSSortDescriptor sortDescriptorWithKey:@"name" ascending:YES ];
    
    NSSortDescriptor *age = [NSSortDescriptor sortDescriptorWithKey:@"age" ascending:YES];
  
    //排序
    NSArray *newArr1 = [arr2 sortedArrayUsingDescriptors:@[age, name]];
    
    for (Person *per in newArr1) {
        NSLog(@"%@ , %ld",per.name, per.age);
    }
           

• 打印结果

2016-06-16 09:54:21.671  遍历和数组排序[8222:657731] 名字xiaoli , 年龄17
2016-06-16 09:54:21.671  遍历和数组排序[8222:657731] 名字tom , 年龄18
2016-06-16 09:54:21.671  集合遍历和数组排序[8222:657731] 名字xiaoming , 年龄18
2016-06-16 09:54:21.671  集合遍历和数组排序[8222:657731] 名字zhangsan , 年龄20
2016-06-16 09:54:21.671  集合遍历和数组排序[8222:657731] 名字xiaoxue , 年龄22

方法 二 ： sortedArrayUsingSeletector 方法

    注意： 字符串比较的是 ASCII 码值大小
    例如：
    NSString *a = @"aaaA";//'A'的ASCII码值是65  
    NSString *b = @"aaaa";//'a'的ASCII码值是97  
    
    // 数组中都是字符串对象
    NSArray *arr = @[@"zhangsan",@"lisi",@"wang"];
    
    
    // @param SEL 方法选择器,@selector (方法名) ,方法的返回值必须是 NSComparisonResult (比较)
    // 注意,这个方法是数组中元素的方法,所以需要数组的排序 ;
    
    NSArray *NewArr = [arr sortedArrayUsingSelector:@selector(compare:)];
    
    for (NSString *string in NewArr) {
        NSLog(@"%@",string);
    }

方法 三 ：自定义类数组排序，例如上面 Person 类的数组中都是 peson 对象,按照 name 升序排序

    Person *per1 = [[Person alloc] initWithName:@"zhangsan" age:20 sex:@"male"];
    
    Person *per2 = [[Person alloc] initWithName:@"xiaoming" age:18 sex:@"male"];
    
    Person *per3 = [[Person alloc] initWithName:@"xiaoxue" age:22 sex:@"female"];
    
    Person *per4 = [[Person alloc] initWithName:@"xiaoli" age:17 sex:@"female"];
    
    Person *per5 = [[Person alloc] initWithName:@"tom" age:18 sex:@"female"];
    
    NSArray *arr2 = @[per1, per2, per3, per4, per5];

    
    
    //姓名 升序
    
    NSArray *NewArr2 = [arr2 sortedArrayUsingSelector:@selector(compareWithNameUP:)];
    
    for (Person *per in NewArr2) {
        NSLog(@"%@",per.name);
    }

    
    // 姓名 降序
    
    NSArray *NewArr3 = [arr2 sortedArrayUsingSelector:@selector(compareWithNameDown:)];
    
    for (Person *per in NewArr3) {
        NSLog(@"%@",per.name);
    }

    
    
    // 根据年龄 进行升序
    
    NSArray *ageUP = [arr2 sortedArrayUsingSelector:@selector(compareWithAgeUP:)];
    
    for (Person *per in ageUP) {
        NSLog(@"%ld",per.age);
    }
    

方法 四： sortedArrayUsingComparator Block块儿

    NSArray *arr = @[@"wang",@"zhang",@"lisi"];
    
    NSArray *newarr = [arr sortedArrayUsingComparator:^NSComparisonResult(id  _Nonnull obj1, id  _Nonnull obj2) {
        
        return [obj1 compare:obj2];//升序
 
    }];
    
    
    for (NSString *string in newarr) {
        NSLog(@"代码块儿：%@",string);
    }

    
    /// 构造类
    Person *per1 = [[Person alloc] initWithName:@"zhangsan" age:20 sex:@"male"];
    
    Person *per2 = [[Person alloc] initWithName:@"xiaoming" age:18 sex:@"male"];
    
    Person *per3 = [[Person alloc] initWithName:@"xiaoxue" age:22 sex:@"female"];
    
    Person *per4 = [[Person alloc] initWithName:@"xiaoli" age:17 sex:@"female"];
    
    Person *per5 = [[Person alloc] initWithName:@"tom" age:18 sex:@"female"];
    
    NSArray *arr2 = @[per1, per2, per3, per4, per5];
   
    // 按照 person 的name 升序排序
    
    NSArray *newarr2 = [arr2 sortedArrayUsingComparator:^NSComparisonResult(Person*  _Nonnull obj1, Person*  _Nonnull obj2) {
        
        return [obj1.name compare:obj2.name ];
    }];
    
    
    for (Person *per in newarr2) {
        NSLog(@"%@", per.name);
    }
 
    // 按照person的 age 降序排序
    NSArray *ageDown = [arr2 sortedArrayUsingComparator:^NSComparisonResult(id  _Nonnull obj1, id  _Nonnull obj2) {
        
        Person *per1 = obj1;
        Person *per2 = obj2;
        
        if (per1.age > per2.age) {
            
            return NSOrderedAscending;// 升序
        }else if (per1.age < per2.age){
        
        //需求降序,前一个小于后一个,两个数掉换一下 Descending 改变if的排序 降序 + dssending (降序) 变为升序 ; 升序(<) + dssending (降序) 变为降序
            return NSOrderedDescending;// 降序
        }else{
            
        return NSOrderedSame;
        }
        
    }];
    
    for (Person *per in ageDown) {
        NSLog(@"%ld", per.age);
    }
    

方法 五： 可变数组排序

    NSMutableArray *mArr = @[@"wang",@"zhang",@"lisi"].mutableCopy;
    
    // 升序排序,数组本身进行了交换, 直接看方法是否有返回值,有返回值为不可变数组
    [mArr sortUsingSelector:@selector(compare:)];