////  Person.h//  谓词////  Created by on 14-11-15.//  Copyright (c) 2014年 Apple. All rights reserved.//#import 
    
     @interface Person : NSObject@property(nonatomic, copy) NSString *name;@property(nonatomic) int age;@property(nonatomic, copy) NSString *email;@end
    

////  Person.m//  谓词////  Created by on 14-11-15.//  Copyright (c) 2014年 Apple. All rights reserved.//#import "Person.h"@implementation Person- (NSString *)description{    return [NSString stringWithFormat:@"name=%@, age=%d, email=%@", _name, _age, _email];}@end

////  main.m//  谓词////  Created by on 14-11-15.//  Copyright (c) 2014年 Apple. All rights reserved.//#import 
    
     #import "Person.h"// cocoa中提供了NSPredicate类，指定过滤器的条件。将符合条件的对象保留下来int main(int argc, const char * argv[]) {    @autoreleasepool {        NSPredicate *predicate = [NSPredicate predicateWithFormat:@"age <= 28"];        //        下面三个是不同过滤条件的方法//        NSPredicate *predicate1 = [NSPredicate predicateWithFormat:@"age <= %d", 22];//        NSPredicate *predicate2 = [NSPredicate predicateWithFormat:@"age <= 100 && age >= 50"];//        记住，字符串一定要加''//        NSPredicate *predicate3 = [NSPredicate predicateWithFormat:@"name in {'jack', 'tom'}"];        NSMutableArray *mutableArray = [[NSMutableArray alloc] init];        for (int i = 0; i < 10; i++) {            Person *person = [[Person alloc] init];            [person setName:@"JACK"];            [person setAge:20 + i];            [person setEmail:@"aa@aa.com"];                        [mutableArray addObject:person];        }                for (Person *p in mutableArray) {            if ([predicate evaluateWithObject:p]) {                NSLog(@"age = %d", p.age);            }        }        //        这种方式过滤后返回一个数组        NSArray *predicateArray = [mutableArray filteredArrayUsingPredicate:predicate];        NSLog(@"%@", predicateArray);    }    return 0;}