//年龄小于30          //定义谓词对象，谓词对象中包含了过滤条件          NSPredicate *predicate = [NSPredicate predicateWithFormat:@"age<%d",30];          //使用谓词条件过滤数组中的元素，过滤之后返回查询的结果          NSArray *array = [persons filteredArrayUsingPredicate:predicate];          NSLog(@"filterArray=%@",array);                    //查询name=1的并且age大于40  与&&        predicate = [NSPredicate predicateWithFormat:@"name='1' && age>40"];          array = [persons filteredArrayUsingPredicate:predicate];          NSLog(@"filterArray=%@",array);      注：对于变量应使用    predicate = [NSPredicate predicateWithFormat:@"name CONTAINS %@&& age>40",str];                    //in(包含)   或||        predicate = [NSPredicate predicateWithFormat:@"self.name IN {'1','2','4'} || self.age IN{30,40}"];                    //name以a开头的          predicate = [NSPredicate predicateWithFormat:@"name BEGINSWITH 'a'"];          //name以ba结尾的          predicate = [NSPredicate predicateWithFormat:@"name ENDSWITH 'ba'"];                    //name中包含字符a的          predicate = [NSPredicate predicateWithFormat:@"name CONTAINS 'a'"];                    //like 匹配任意多个字符          //name中只要有s字符就满足条件          predicate = [NSPredicate predicateWithFormat:@"name like '*s*'"];          //?代表一个字符，下面的查询条件是：name中第二个字符是s的          predicate = [NSPredicate predicateWithFormat:@"name like '?s'"];