iOS NSPredicate

什么是谓词？  

谓词是通过NSPRedicate，是通过给定的逻辑条件作为约束条件，完成对数据的筛选。  

NSArray *array = [[NSArrayalloc]initWithObjects:@"zhangsan",@"lisi",@"wangwu",@"xiaoliu",@"wulili",nil];

    NSPredicate *preBegin= [NSPredicatepredicateWithFormat:@"SELF beginswith[c] %@",@"w"];

    //通过filteredArrayUsingPredicate过滤数组

    NSArray *preBeginArray = [arrayfilteredArrayUsingPredicate:preBegin];

    NSPredicate *preContain = [NSPredicatepredicateWithFormat:@"SELF contains[c] %@",@"i"];

    NSArray *preContainArray = [arrayfilteredArrayUsingPredicate:preContain];

    NSLog(@"preBeginArray>>%@",preBeginArray);

    NSLog(@"preContainArray>>%@",preContainArray);

    //初始化一个查询条件

    NSPredicate *predicate = [NSPredicatepredicateWithFormat:@"SELF IN %@",@[@"bei",@"jing",@"huan",@"ying",@"ni"]];

    if ([predicateevaluateWithObject:@"huan"]) {//判断数据在不在结果集中

        NSLog(@"huan");

    };