iOS NSPredicate

什麼是謂詞？  

謂詞是通過NSPredicate，是通過給定的邏輯條件作爲約束條件，完成對數據的篩選。  

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

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

    //通過filteredArrayUsingPredicate過濾數組

    NSArray *preBeginArray = [array filteredArrayUsingPredicate:preBegin];

    

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

    NSArray *preContainArray = [array filteredArrayUsingPredicate:preContain];

    

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

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

    

    

    //初始化一個查詢條件

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

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

        NSLog(@"huan");

    };