NSPredicate使用笔记

1.常用方法

//    1.创建NSPredicate（相当于创建一个过滤条件）
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"过滤条件"];
//    2.判断指定的对象是否满足NSPredicate创建的过滤条件
    [predicate evaluateWithObject:person];
//    3.过滤出符合条件的对象（返回所有符合条件的对象）
    NSArray *persons = [array filteredArrayUsingPredicate:predicate];

    NSArray *arrPersons = @[
                          [[Person alloc] initWithName:@"Mark" gender:@"M" age:36],
                          [[Person alloc] initWithName:@"Andy" gender:@"F" age:29],
                          [[Person alloc] initWithName:@"Jack" gender:@"M" age:20],
                          [[Person alloc] initWithName:@"Jobs" gender:@"M" age:59],
                          [[Person alloc] initWithName:@"Elizabeth" gender:@"F" age:81],
                          ];
    ```

2.比较运算符 >,<,==,>=,<=,!=,AND,&&,OR,||

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"age>50 AND gender='F'"]; // 注意这个语法里面字符串要用单引号
NSArray *result = [arrPersons filteredArrayUsingPredicate:predicate];
// 打印输出结果
NSLog(@"%@",result);
/*
 输出结果:
 (
 "Elizabeth-F-81"
 )
 */

3.范围运算符，in(则表示在后面的{}中是否包含)，between(在某个范围内，如：age between{15,25}等价于 15<=age<=25

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"age between{20,30}"];
NSArray *result = [arrPersons filteredArrayUsingPredicate:predicate];
// 打印输出结果
NSLog(@"%@",result);
/*
 输出结果:
 (
 "Andy-F-29",
 "Jack-M-20"
 )
 */


//场景3
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"age in{20,30}"];
NSArray *result = [arrPersons filteredArrayUsingPredicate:predicate];
// 打印输出结果
NSLog(@"%@",result);
/*
 输出结果:
 (
 "Jack-M-20"
 )
 */

//场景4
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name in{'Jobs','Mark'}"]; //当条件是NSString时 in 和 between 结果一致
NSArray *result = [arrPersons filteredArrayUsingPredicate:predicate];
// 打印输出结果
NSLog(@"%@",result);
/*
 输出结果:
 (
 "Mark-M-36",
 "Jobs-M-59"
 )
 */

4.对象本身self 如@"SELF == 'Apple'"（也可以是NSNumber）

NSArray *arr = @[@"Apple",@"Mac",@"iPhone"];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF == 'Apple'"];

NSArray *result = [arr filteredArrayUsingPredicate:predicate];
// 打印输出结果
NSLog(@"%@",result);
/*
 输出结果:
 (
 Apple
 )
 */

5.字符串相关

：BEGINSWITH、ENDSWITH、CONTAINS
例：@"name CONTAINS[cd] 'ang'" //包含某个字符串
@"name BEGINSWITH[c] 'sh'" //以某个字符串开头
@"name ENDSWITH[d] 'ang'" //以某个字符串结束
//场景6
NSArray *arr = @[@"yangjie",@"zhangsan",@"lisi"];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"self contains[cd] 'ng'"];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"self beginswith[c] 'y'"];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"self endswith[d] 'i'"];

6.通配符：LIKE

// 例：@"name LIKE[cd] 'er'" //代表通配符,Like也接受[cd].
// @"name LIKE[cd] '???er'"
NSArray *arr = @[@"yangjie",@"zhangsan",@"lisi",@"ang",@"tangddd",@"fangxxx"];
NSPredicate predicate = [NSPredicate predicateWithFormat:@"self like[cd] 'ang'"];
// 注意这个语法里面字符串要用单引号

NSArray *result = [arr filteredArrayUsingPredicate:predicate];
// 打印输出结果
NSLog(@"%@",result);
// 打印输出结果
NSLog(@"%@",result);
/*
 输出结果:
 (
 ang
 )
 */

7.正则表达式：MATCHES

NSPredicate 使用MATCHES 匹配正则表达式，正则表达式的写法采用international components
for Unicode (ICU)的正则语法。


例：NSString *regex = @"^A.+e$"; //以A开头，e结尾
@"name MATCHES %@",regex

        例：
    NSString *regex = @"^A.+e$";//以A 开头，以e 结尾的字符。
NSPredicate *pre= [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];
if([pre evaluateWithObject: @"Apple"]){
    printf("YES\n");
}else{  
    printf("NO\n");  
}