谓词(过滤)

个人认为微词是个很不错的东西

1.自定义对象

@interface Person : NSObject

@property(nonatomic , copy)NSString * name;

@property(nonatomic , assign)int age;

@property (nonatomic , retain)NSArray * familys;

@end

2.简单实用（数据比较）

- (void)testObject1 {
    Person *person = [[Person alloc] init];
    person.name = @"gulong";
    person.age = 24;
   //整形比较
    NSPredicate * pred = [NSPredicate predicateWithFormat:@"age > 25"];
    BOOL match = [pred evaluateWithObject:person];
    NSLog(@"%s",(match)?"YES":"NO");
   //printf: NO
}

3.通配符和正则

- (void)testObject2 {
    /* 
     BEGINSWITH：检查某个字符串是否以另一个字符串开头。
     ENDSWITH：检查某个字符串是否以另一个字符串结尾。
     CONTAINS：检查某个字符串是否以另一个字符串内部。
     [c]不区分大小写[d]不区分发音符号即没有重音符号[cd]既不区分大小写，又不区分发音符号。
     */
    Person *person = [[Person alloc] init];
    person.name = @"gulong";
    person.age = 24;
    
    /* 通配符 */
    NSPredicate *predicate1 = [NSPredicate predicateWithFormat:@"name LIKE[cd] '*er*'"];
         //*代表通配符Like还接受[cd].
    predicate1 = [NSPredicate predicateWithFormat:@"name LIKE[cd] '???er*'"];
    //?只匹配一个字符并且还可以接受[cd].
    //*表示有多个占位符
    /* 正则匹配 */
    NSString *regex = @"[A-Za-z]+";
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];
    
    if ([predicate evaluateWithObject:@"huang"]) {
        NSLog(@"字符串是否为纯字母");
    }
    //printf 字符串是否为纯字母

}

4.数组的过滤1（里面的每个对象都是字符串）

- (void)testArray1 {
    NSArray *array = [[NSArray alloc]initWithObjects:@"beijing",@"shanghai",@"guangzou",@"wuhan", nil];
    NSString *string = @"ang";
  //获取带有ang的所有字符串，然后形成一个数组
    NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF CONTAINS %@",string];
    NSLog(@"%@",[array filteredArrayUsingPredicate:pred]);
    //printf: shanghai,guangzou
}

 5.数组的过滤2 （使用自定义的person类）

- (void)testArray2 {
    Person *person1 = [[Person alloc] init];
    person1.name = @"long";
    person1.age = 23;
    
    Person *person2 = [[Person alloc] init];
    person2.name = @"gu";
    person2.age = 23;
    
    Person *person3 = [[Person alloc] init];
    person3.name = @"long";
    person3.age = 24;

    NSArray *persons = @[person1,person2,person3];
    //直接使用对象里面的属性就可以了，不能使用数组的某个对象名（其实format里面使用 “＝” 和 “＝＝”都是一样可行的)
     NSPredicate *pred = [NSPredicate predicateWithFormat:@"name == 'long'"]; //相等
    NSPredicate *pred = [NSPredicate predicateWithFormat:@"name == %@",@"long"]; //相等
    NSPredicate *pred = [NSPredicate predicateWithFormat:@"age == %d",23]; //相等
    NSPredicate *pred = [NSPredicate predicateWithFormat:@"age = 23",]; //相等
    // (age > 23) AND (age < 26) AND 两者都要满足，OR 两种满足其一就可    
    // age between {23,26} 从23 到26之间 //@"name IN { 'Herbie', 'Snugs', 'Badger', 'Flap' }"; 
    //包含在其中用IN 
    NSArray *array = [persons filteredArrayUsingPredicate:pred]; 
    NSLog(@"array %@",[array description]); 
}

6.数组过滤3（对象里面还有数据）

@property (nonatomic , retain)NSArray * familys;    //person.h

- (void)testArray3 {
    Person *person1 = [[Person alloc] init];
    person1.name = @"huang";
    person1.age = 23;
    person1.familys = @[@"zhuge",@"zhangfei",@"liubei"];
    
    Person *person2 = [[Person alloc] init];
    person2.name = @"gu";
    person2.age = 23;
    person2.familys = @[@"suiquan",@"huanggai",@"lusun"];
    
    Person *person3 = [[Person alloc] init];
    person3.name = @"huang";
    person3.age = 24;
    person3.familys = @[@"caochao",@"xiahou",@"caozhi"];
    
    NSArray *persons = @[person1,person2,person3];
    /*
     * 数组包含时必须为 整个字符串，不是是部分（比如 huanggai 的 huang；这样是无数据的）
     */
    NSPredicate *pred = [NSPredicate predicateWithFormat:@"familys CONTAINS 'huanggai'"];

    /*
     * 字符串包含时必须为 整个字符串，不是是部分（比如 huanggai 的 huang；是有用数据的）
     */
    NSPredicate *pred = [NSPredicate predicateWithFormat:@"name CONTAINS 'huanggai'"];

    NSArray *array = [persons filteredArrayUsingPredicate:pred]; NSLog(@"array %@",[array description]); //打印 person2 }