iOS 中的特殊类

NSPredicate

• NSPredicate 是预测的意思，但我们常翻译成谓词。
• 使用NSPredicate可以定义模糊查找条件，根据一定的条件从一个数组中快速找出符合一定条件的元素对象。

• 可以直接搜索对象
• 可以使用 >,<,==,>=,<=,!=来进行判断数据

@interface Person : NSObject

@property (nonatomic, strong) NSString *name;
@property (nonatomic, assign) int age;

@end

self.array = [[NSMutableArray alloc]init];
    
for (int i = 0; i < 10; i++) {
    
    Person *p = [[Person alloc] init];
    p.name = [NSString stringWithFormat:@"Mr.chen %d", i];
    p.age = i * 10;
    [self.array addObject:p];
}
    
NSPredicate *perdicate = [NSPredicate predicateWithFormat:@"age>50"];
NSArray *arr  = [self.array filteredArrayUsingPredicate:perdicate];
NSLog(@"%@",arr);

// 打印结果
(
    "name:Mr.chen 6, age:60",
    "name:Mr.chen 7, age:70",
    "name:Mr.chen 8, age:80",
    "name:Mr.chen 9, age:90"
)

NSArray *arr1 = @[@1, @2, @3, @43, @6, @60];


NSPredicate *perdicate = [NSPredicate predicateWithFormat:@"SELF == 6"];
NSArray *temp = [arr1 filteredArrayUsingPredicate:perdicate];
NSLog(@"%@", temp);

//打印结果
(
    6
)

• 可以使用 SELF 关键字代表自己
• in: arr1 和 arr2的交集

NSArray *arr1 = @[@1, @2, @3, @43, @6];
NSArray *arr2 = @[@2, @6];
    
NSPredicate *perdicate = [NSPredicate predicateWithFormat:@"SELF in %@", arr2];
NSArray *temp = [arr1 filteredArrayUsingPredicate:perdicate];
NSLog(@"%@", temp);

// 打印结果
(
    2,
    6
)

• BETWEEN 获取一定范围的值

NSArray *arr1 = @[@1, @2, @3, @43, @6, @60];

NSPredicate *perdicate = [NSPredicate predicateWithFormat:@"SELF BETWEEN{1,20}"];
NSArray *temp = [arr1 filteredArrayUsingPredicate:perdicate];
NSLog(@"%@", temp);

// 打印结果
(
    1,
    2,
    3,
    6
)

• BEGINSWITH 以某个字符串开头
• ENDSWITH 以某个字符串结尾
• CONTAINS 是否包含某个字符串

NSArray *arr1 = @[@"zhang3", @"wang4", @"lihu"];

NSPredicate *perdicate = [NSPredicate predicateWithFormat:@"SELF BEGINSWITH[cd] 'z' "];
NSArray *temp = [arr1 filteredArrayUsingPredicate:perdicate];
NSLog(@"%@", temp);

// 打印结果
(
    zhang3
)

• 还可以使用LIKE它后面可以写[cd]格式符号, * 表示通配符

NSArray *arr1 = @[@"zhang3", @"wang4", @"lihu"];

NSPredicate *perdicate = [NSPredicate predicateWithFormat:@"SELF LIKE[cd] '*n*' "];
NSArray *temp = [arr1 filteredArrayUsingPredicate:perdicate];
NSLog(@"%@", temp);

// 打印结果
(
    zhang3,
    wang4
)

• 可以使用数组、字典、Data

• 更多条件字符看苹果官方文档

NSSortDescriptor

• NSSortDescriptor 我们可以用它来排序

self.array = [[NSMutableArray alloc]init];

for (int i = 0; i < 12; i++) {

    Person *p = [[Person alloc] init];
    p.name = [NSString stringWithFormat:@"Mr.chen %d", i];
    if (i > 9) {
        p.age = 20;
    } else {
        p.age = arc4random_uniform(100);
    }
    p.money = arc4random_uniform(1000000000) * arc4random_uniform(1000000000) / 9 / 7;
    [self.array addObject:p];
}
    
NSLog(@"%@",self.array);

NSSortDescriptor *ageSD = [NSSortDescriptor sortDescriptorWithKey:@"age" ascending:YES];
NSSortDescriptor *moneySD = [NSSortDescriptor sortDescriptorWithKey:@"money" ascending:NO];
    
NSArray *arr = [self.array sortedArrayUsingDescriptors:@[ageSD, moneySD]];
    
NSLog(@"%@",arr);

// 打印结果

self.array = (
    "name : Mr.chen 0, age : 38 , money : 39527952.00",
    "name : Mr.chen 1, age : 6 , money : 44344428.00",
    "name : Mr.chen 2, age : 39 , money : 37546996.00",
    "name : Mr.chen 3, age : 31 , money : 42419204.00",
    "name : Mr.chen 4, age : 51 , money : 37637156.00",
    "name : Mr.chen 5, age : 28 , money : 48236272.00",
    "name : Mr.chen 6, age : 80 , money : 29929636.00",
    "name : Mr.chen 7, age : 56 , money : 17334832.00",
    "name : Mr.chen 8, age : 1 , money : 53353300.00",
    "name : Mr.chen 9, age : 13 , money : 4750739.00",
    "name : Mr.chen 10, age : 20 , money : 60696080.00",
    "name : Mr.chen 11, age : 20 , money : 39092136.00"
)
arr = (
    "name : Mr.chen 8, age : 1 , money : 53353300.00",
    "name : Mr.chen 1, age : 6 , money : 44344428.00",
    "name : Mr.chen 9, age : 13 , money : 4750739.00",
    "name : Mr.chen 10, age : 20 , money : 60696080.00",
    "name : Mr.chen 11, age : 20 , money : 39092136.00",
    "name : Mr.chen 5, age : 28 , money : 48236272.00",
    "name : Mr.chen 3, age : 31 , money : 42419204.00",
    "name : Mr.chen 0, age : 38 , money : 39527952.00",
    "name : Mr.chen 2, age : 39 , money : 37546996.00",
    "name : Mr.chen 4, age : 51 , money : 37637156.00",
    "name : Mr.chen 7, age : 56 , money : 17334832.00",
    "name : Mr.chen 6, age : 80 , money : 29929636.00"
)

• [NSSortDescriptor sortDescriptorWithKey:@"money" ascending:NO] 直接用内方法创建
• ascending YES，为升序，NO 为降序
• 当两个一起用的时候以第一个为基础的如果有相同在排序第二个，以此类推