什么是謂詞？  

謂詞是通過NSPRedicate，是通過給定的邏輯條件作為約束條件，完成對數據的篩選。  

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

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

    //通過filteredArrayUsingPredicate過濾數組

    NSArray *preBeginArray = [arrayfilteredArrayUsingPredicate:preBegin];

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

    NSArray *preContainArray = [arrayfilteredArrayUsingPredicate:preContain];

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

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

    //初始化一個查詢條件

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

    if ([predicateevaluateWithObject:@"huan"]) {//判斷數據在不在結果集中

        NSLog(@"huan");

    };