iOS中关于NSPredicate的使用

一般我们最多的是用NSPredicate来做字符串的正则验证

    NSMutableArray *people_arr = [NSMutableArray new];

    NSMutableArray *filter_arr = [NSMutableArray new];

    for (int i = 0; i < 10; i++) {

        People *people = [People new];

        people.name = @[@"jack",@"jester",@"jester",@"joce",@"joke",@"java",@"amy",@"jason",@"mike",@"jwt"];

        people.age = 15+i;

        people.gender = i%2? @"男":@"女";

        people.address = @[@"郑州",@"上海",@"济南",@"北京",@"杭州"][arc4random()%5];

        for (int j = 0; j < 3; j ++) {

            Employee *employee = [Employee new];

            employee.employeeId = i+arc4random()%3;

            employee.department = @[@"研发部",@"人事部",@"财务部",@"运营部"][arc4random()%4];

            [people.employees addObject:employee];

        }

        [people_arr addObject:people];

        arc4random()%3 == 0 ? [filter_arr addObject:people] : NULL;

    }

以上部分，便是原始数据的生成

具体NSPredicate的使用代码：

    // self 表示数组元素/字符串本身

    // 比较运算符 =/==(等于)、>=/=>(大于等于)、<=/=<(小于等于)、>(大于)、<(小于)、!=/<>(不等于)

    //NSPredicate *pre = [NSPredicate predicateWithFormat:@"self = %@",[people_arr lastObject]];//比较数组元素相等

    //NSPredicate *pre = [NSPredicate predicateWithFormat:@"address = %@",[(People *)[people_arr lastObject] address]];//比较数组元素中某属性相等

    NSPredicate *pre = [NSPredicate predicateWithFormat:@"age in {18,21}"];//比较数组元素中某属性值在这些值中

    //NSPredicate *pre = [NSPredicate predicateWithFormat:@"age between {18,21}"];//比较数组元素中某属性值大于等于左边的值，小于等于右边的值

    // 逻辑运算符 and/&&(与)、or/||(或)、not/!(非)

    //NSPredicate *pre = [NSPredicate predicateWithFormat:@"address = %@ && age between {19,22}",[(People *)[people_arr lastObject] address]];

    // 字符串比较运算符 beginswith(以*开头)、endswith(以*结尾)、contains(包含)、like(匹配)、matches(正则)

    // [c]不区分大小写 [d]不区分发音符号即没有重音符号 [cd]既 又

    //NSPredicate *pre = [NSPredicate predicateWithFormat:@"name beginswith[cd] 'ja'"];

    //NSPredicate *pre = [NSPredicate predicateWithFormat:@"name matches '^[a-zA-Z]{4}$'"];

    //集合运算符 some/any:集合中任意一个元素满足条件、all:集合中所有元素都满足条件、none:集合中没有元素满足条件、in:集合中元素在另一个集合中

    //NSPredicate *pre = [NSPredicate predicateWithFormat:@"all employees.employeeId in {7,8,9}"];

    //NSPredicate *pre = [NSPredicate predicateWithFormat:@"self in %@",filter_arr];

    // $K：用于动态传入属性名、%@：用于动态设置属性值(字符串、数字、日期对象)、$(value)：可以动态改变

    //NSPredicate *pre = [NSPredicate predicateWithFormat:@"%K > $age",@"age"];

    //pre = [pre predicateWithSubstitutionVariables:@{@"age":@21}];

    // NSCompoundPredicate 相当于多个NSPredicate的组合

    //NSCompoundPredicate *compPre = [NSCompoundPredicate andPredicateWithSubpredicates:@[[NSPredicate predicateWithFormat:@"age > 19"],[NSPredicate predicateWithFormat:@"age < 21"]]];

    // 暂时没找到用法

    //NSComparisonPredicate *compPre = [NSComparisonPredicate predicateWithLeftExpression:[NSExpression expressionForKeyPath:@"name"] rightExpression:[NSExpression expressionForVariable:@"ja"] modifier:NSAnyPredicateModifier type:NSBeginsWithPredicateOperatorType options:NSNormalizedPredicateOption];

    //[people_arr filterUsingPredicate:compPre];

    NSPredicate *pre = [NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary *bindings) {

        return [evaluatedObject age] > 21;

    }];

    // NSPredicate 不影响原数组，返回数组即为过滤结果

    //NSArray *temp_arr = [people_arr filteredArrayUsingPredicate:pre];

    //NSLog(@"%@", temp_arr);

    // NSPredicate 原数组数据即为过滤结果

    [people_arr filterUsingPredicate:pre];

    NSLog(@"%@", people_arr);