KVC(1) - 进阶用法1

首先创建一个Person类，在.h文件中定义属性

#import <Foundation/Foundation.h>

@interface TZPerson : NSObject

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

@end

在ViewController中作如下测试

KVC字典操作

/// KVC字典操作
- (void) dictionaryTest {
    TZPerson* p = [TZPerson new];
    
    NSDictionary* dict = @{
                           @"name":@"Tom",
                           @"age":@18,
                           @"nick":@"Cat",
                           @"height":@180,
                           @"dd":@"helo"
                           };
    
    [p setValuesForKeysWithDictionary:dict];
    NSLog(@"p.name = %@, p.age = %d, p.nick =%@, p.height = %f", p.name, p.age, p.nick, p.height);
    
    NSArray* keys = @[@"name", @"age"];
    NSDictionary* dict1 = [p dictionaryWithValuesForKeys:keys];

    NSLog(@"%@", dict1);
}

自定Key值要和Person属性对应，否者就会出现异常，下面是解决异常办法，在Person类中实现：

 //赋值key值不存在
- (void) setValue:(id)value forUndefinedKey:(NSString *)key {
    NSLog(@"key = %@值不存在 ", key);
}

KVC消息传递 array

- (void) arrayKVCTest {
    NSArray* arr = @[@"Monday", @"Tuesday", @"Wednesday"];

//length、lowercaseString、uppercaseString...都是NSString的成员变量
    NSArray* lengthArr = [arr valueForKey:@"length"];
    NSLog(@"%@", lengthArr);
    
    NSArray* lowercaseArr = [arr valueForKey:@"lowercaseString"];
    NSLog(@"%@", lowercaseArr);
}

聚合操作符

/// 聚合操作符  @avg、@count、@max、@min、@sum
- (void) contrainerTest {
    
    NSMutableArray* students = [NSMutableArray array];
    for (int i = 0; i < 6; i++) {
        TZPerson* student = [TZPerson new];
        NSDictionary* dict = @{
                               @"name":@"Tom",
                               @"age":@(18+i),
                               @"nick":@"Cat",
                               @"height":@(1.65 + 0.02*arc4random_uniform(6)),
                               };
        [student setValuesForKeysWithDictionary:dict];
        [students addObject:student];
    }
    
    NSLog(@"%@", [students valueForKey:@"height"]);
    
    /// 平均身高    @聚合操作符.属性
    float avg = [[students valueForKeyPath:@"@avg.height"] floatValue];
    NSLog(@"%f", avg);

}

数组操作符

@distinctUnionOfObjects ： 去重
@unionOfObjects ： 不去重

/// 数组操作符 @distinctUnionOfObjects @unionOfObjects
- (void) contrainerArrayTest {
    
    NSMutableArray* students = [NSMutableArray array];
    for (int i = 0; i < 6; i++) {
        TZPerson* student = [TZPerson new];
        NSDictionary* dict = @{
                               @"name":@"Tom",
                               @"age":@(18+i),
                               @"nick":@"Cat",
                               @"height":@(1.65 + 0.02*arc4random_uniform(6)),
                               };
        [student setValuesForKeysWithDictionary:dict];
        [students addObject:student];
    }
    
    NSLog(@"%@", [students valueForKey:@"height"]);
    
    
    NSArray* arr = [students valueForKeyPath:@"@distinctUnionOfObjects.height"];
    NSLog(@"arr = %@", arr);
    
    NSArray* arr1 = [students valueForKeyPath:@"@unionOfObjects.height"];
    NSLog(@"arr1 = %@", arr1);
}

嵌套操作符

@distinctUnionOfArrays
@unionOfArrays
@distinctUnionOfSets

/// 嵌套集合(array&set)操作 @distinctUnionOfArrays @unionOfArrays @distinctUnionOfSets
- (void) containerNestingTest {
    
    NSMutableArray* students = [NSMutableArray array];
    for (int i = 0; i < 6; i++) {
        TZPerson* student = [TZPerson new];
        NSDictionary* dict = @{
                               @"name":@"Tom",
                               @"age":@(18+i),
                               @"nick":@"Cat",
                               @"height":@(1.65 + 0.02*arc4random_uniform(6)),
                               };
        [student setValuesForKeysWithDictionary:dict];
        [students addObject:student];
    }
    
    NSMutableArray* students1 = [NSMutableArray array];
    for (int i = 0; i < 6; i++) {
        TZPerson* student = [TZPerson new];
        NSDictionary* dict = @{
                               @"name":@"Tom",
                               @"age":@(18+i),
                               @"nick":@"Cat",
                               @"height":@(1.65 + 0.02*arc4random_uniform(6)),
                               };
        [student setValuesForKeysWithDictionary:dict];
        [students1 addObject:student];
    }
    
    // 嵌套数组
    NSArray* nestArr = @[students, students1];
    
    
    NSArray* arr = [nestArr valueForKeyPath:@"@distinctUnionOfArrays.height"];
    NSLog(@"arr = %@", arr);
    
    NSArray* arr1 = [nestArr valueForKeyPath:@"@unionOfArrays.height"];
    NSLog(@"arr1 = %@", arr1);
    
}

- (void) containerNestingTest1 {
    
    NSMutableSet* students = [NSMutableSet set];
    for (int i = 0; i < 6; i++) {
        TZPerson* student = [TZPerson new];
        NSDictionary* dict = @{
                               @"name":@"Tom",
                               @"age":@(18+i),
                               @"nick":@"Cat",
                               @"height":@(1.65 + 0.02*arc4random_uniform(6)),
                               };
        [student setValuesForKeysWithDictionary:dict];
        [students addObject:student];
    }
    
    NSLog(@"students = %@", [students valueForKey:@"height"]);
    
    NSMutableSet* students1 = [NSMutableSet set];
    for (int i = 0; i < 6; i++) {
        TZPerson* student = [TZPerson new];
        NSDictionary* dict = @{
                               @"name":@"Tom",
                               @"age":@(18+i),
                               @"nick":@"Cat",
                               @"height":@(1.65 + 0.02*arc4random_uniform(6)),
                               };
        [student setValuesForKeysWithDictionary:dict];
        [students1 addObject:student];
    }
    
     NSLog(@"students1 = %@", [students1 valueForKey:@"height"]);
    
    NSSet* nestSet = [NSSet setWithObjects:students, students1, nil];
    
    NSArray* arr1 = [nestSet valueForKeyPath:@"@distinctUnionOfSets.height"];
    NSLog(@"arr1 = %@", arr1);
}

集合代理对象 (重要)