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03--KVC/KVO本质01--KVC 初探

03--KVC/KVO本质01--KVC 初探

作者: 修_远 | 来源:发表于2020-07-02 22:32 被阅读0次

    [TOC]

    本章介绍 KVC 的常见用法

    准备条件

    • SRPerson 类
    typedef struct {
    float x, y, z;
} ThreeFloats;

@interface SRPerson : NSObject
{
    @public
    NSString* myName;
}

@property (nonatomic, copy) NSString *name;
@property (nonatomic, strong) NSArray *array;
@property (nonatomic, strong) NSMutableArray *mArray;
@property (nonatomic, assign) int age;
@property (nonatomic) ThreeFloats threeFloats;
@property (nonatomic, strong) SRStudent *student;

@end
    • SRStudent 类
    @interface SRStudent : NSObject

@property (nonatomic, copy)   NSString          *name;
@property (nonatomic, copy)   NSString          *subject;
@property (nonatomic, copy)   NSString          *nick;
@property (nonatomic, assign) int               age;
@property (nonatomic, assign) int               length;
@property (nonatomic, strong) NSMutableArray    *penArr;

@end

    一般 setter 方法

    • 测试代码
    person.name = @"SR_Name";
person.age  = 18;
person->myName = @"My_Name";
NSLog(@"%@", person);
    • 输出
    [myName] : My_Name
[name] : SR_Name
[array] : (null)
[mArray] : (null)
[age] : 18
[threeFloats] : 0.000000, 0.000000, 0.000000
[student] : (null)

    1. Key-Value Coding (KVC) : 基本类型

    • 测试代码
    [person setValue:@"KVC_Name" forKey:@"name"];
[person setValue:@19 forKey:@"age"];
[person setValue:@"KVC_My_Name" forKey:@"myName"];
NSLog(@"%@", person);
    • 输出
    [myName] : KVC_My_Name
[name] : KVC_Name
[array] : (null)
[mArray] : (null)
[age] : 19
[threeFloats] : 0.000000, 0.000000, 0.000000
[student] : (null)

    2. KVC 集合类型

    • 测试代码
    person.array = @[@"1", @"2", @"3"];
NSLog(@"%@", person);
// 更改 array 的值 : 通过修改 array
NSArray* tempArr1 = [person valueForKey:@"array"];
tempArr1 = @[@"110", @"2", @"3"];
[person setValue:tempArr1 forKey:@"array"];
NSLog(@"%@", person);
// 更改 array 的值 : 通过 KVC 的方式
NSMutableArray* tempArr2 = [person mutableArrayValueForKey:@"array"];
tempArr2[0] = @"120";
NSLog(@"%@", person);
    • 输出
    [myName] : KVC_My_Name
[name] : KVC_Name
[array] : (
    1,
    2,
    3
)
[mArray] : (null)
[age] : 19
[threeFloats] : 0.000000, 0.000000, 0.000000
[student] : (null)

    [myName] : KVC_My_Name
[name] : KVC_Name
[array] : (
    110,
    2,
    3
)
[mArray] : (null)
[age] : 19
[threeFloats] : 0.000000, 0.000000, 0.000000
[student] : (null)

    [myName] : KVC_My_Name
[name] : KVC_Name
[array] : (
    120,
    2,
    3
)
[mArray] : (null)
[age] : 19
[threeFloats] : 0.000000, 0.000000, 0.000000
[student] : (null)

    3. 集合操作符

    3.1 集合操作符 : 字典操作

    • 测试代码
    - (void)dictionaryTest {
    NSDictionary* dict = @{
        @"name" : @"dict_name",
        @"nick" : @"dn",
        @"subject" : @"iOS",
        @"age" : @18,
        @"length" : @188
    };
    
    SRStudent* student = [[SRStudent alloc] init];
    // 字典转模型
    [student setValuesForKeysWithDictionary:dict];
    NSLog(@"%@", student);
    // 键数组转模型到字典
    NSArray* keyArr = @[@"name", @"age"];
    NSDictionary* dic = [student dictionaryWithValuesForKeys:keyArr];
    NSLog(@"dic : %@", dic);
}
    • 输出
    2020-06-23 13:44:15.364904+0800 001--KVC初探[9196:195892] SRStudent
[name] : dict_name
[subject] : iOS
[nick] : dn
[age] : 18
[length] : 188
[penArr] : (null)
2020-06-23 13:44:15.365225+0800 001--KVC初探[9196:195892] dic : {
    age = 18;
    name = "dict_name";
}

    3.2 集合操作符 : KVC消息传递

    • 测试代码
    - (void)arrayMessagePass {
    NSArray* array = @[@"ZhangSan", @"LiSi", @"WangWu"];
    // 获取 value 的长度 : length
    NSArray* lenStr = [array valueForKeyPath:@"length"];
    NSLog(@"lenStr : %@", lenStr);
    // 将 value 转成小写字母 : lowercaseString
    NSArray* lowStr = [array valueForKeyPath:@"lowercaseString"];
    NSLog(@"lowStr : %@", lowStr);
}
    • 输出
    2020-06-23 13:44:15.365425+0800 001--KVC初探[9196:195892] lenStr : (
    8,
    4,
    6
)
2020-06-23 13:44:15.365533+0800 001--KVC初探[9196:195892] lowStr : (
    zhangsan,
    lisi,
    wangwu
)

    3.3 集合操作符 : 集合操作符

    • 测试代码
    // @avg     : 平均数
// @count   : 计数
// @max     : 最大值
// @min     : 最小值
// @sum     : 求和
- (void)aggregationOperator {
    NSMutableArray* sArr = [NSMutableArray array];
    for (int i=0; i<6; i++) {
        SRStudent* s = [SRStudent new];
        NSDictionary* dict = @{
            @"name" : @"xiaoming",
            @"age" : @(18+i),
            @"nick" : @"dabai",
            @"length" : @(180 + 2*arc4random_uniform(5)),
        };
        [s setValuesForKeysWithDictionary:dict];
        [sArr addObject:s];
    }
    NSLog(@"length >>>> %@", [sArr valueForKey:@"length"]);
    
    float avg = [[sArr valueForKeyPath:@"@avg.length"] floatValue];
    NSLog(@"avg : %f", avg);
    
    int count = [[sArr valueForKeyPath:@"@count.length"] intValue];
    NSLog(@"count : %d", count);
    
    int max = [[sArr valueForKeyPath:@"@max.length"] intValue];
    NSLog(@"max : %d", max);
    
    int min = [[sArr valueForKeyPath:@"@min.length"] intValue];
    NSLog(@"min : %d", min);
    
    int sum = [[sArr valueForKeyPath:@"@sum.length"] intValue];
    NSLog(@"sumsum : %d", sum);
}
    • 输出
    2020-06-23 13:44:15.365670+0800 001--KVC初探[9196:195892] length >>>> (
    184,
    180,
    188,
    186,
    186,
    184
)
2020-06-23 13:44:15.366726+0800 001--KVC初探[9196:195892] avg : 184.666672
2020-06-23 13:44:15.366918+0800 001--KVC初探[9196:195892] count : 6
2020-06-23 13:44:15.367035+0800 001--KVC初探[9196:195892] max : 188
2020-06-23 13:44:15.367305+0800 001--KVC初探[9196:195892] min : 180
2020-06-23 13:44:15.367608+0800 001--KVC初探[9196:195892] sumsum : 1108

    3.4 数组操作符 @distinctUnionOfObjects @unionOfObjects

    • 测试代码
    - (void)arrayOperator {
    NSMutableArray* sArr = [NSMutableArray array];
    for (int i=0; i<6; i++) {
        SRStudent* s = [SRStudent new];
        NSDictionary* dict = @{
            @"name" : @"xiaoming",
            @"age" : @(18+i),
            @"nick" : @"dabai",
            @"length" : @(180 + 2*arc4random_uniform(5)),
        };
        [s setValuesForKeysWithDictionary:dict];
        [sArr addObject:s];
    }
    NSLog(@"length >>>> %@", [sArr valueForKey:@"length"]);
    // 返回操作对象指定属性的集合
    NSArray* arr1 = [sArr valueForKeyPath:@"@unionOfObjects.length"];
    NSLog(@"unionOfObjects arr : %@", arr1);
    // 返回操作对象指定属性的集合 -- 去重
    NSArray* arr2 = [sArr valueForKeyPath:@"@distinctUnionOfObjects.length"];
    NSLog(@"distinctUnioOfObjects arr : %@", arr2);
}
    • 输出
    2020-06-23 13:44:15.368240+0800 001--KVC初探[9196:195892] length >>>> (
    180,
    182,
    180,
    182,
    184,
    188
)
2020-06-23 13:44:15.368883+0800 001--KVC初探[9196:195892] unionOfObjects arr : (
    180,
    182,
    180,
    182,
    184,
    188
)
2020-06-23 13:44:15.369436+0800 001--KVC初探[9196:195892] distinctUnioOfObjects arr : (
    182,
    188,
    184,
    180
)

    3.5 嵌套集合(array&set)操作 @distinctUnionOfArrays @unionOfArrays @distinctUnionOfSets

    • 测试代码
    - (void)arrayNesting {
    NSMutableArray* sArr1 = [NSMutableArray array];
    for (int i=0; i<6; i++) {
        SRStudent* s = [SRStudent new];
        NSDictionary* dict = @{
            @"name" : @"xiaoming",
            @"age" : @(18+i),
            @"nick" : @"dabai",
            @"length" : @(180 + 2*arc4random_uniform(5)),
        };
        [s setValuesForKeysWithDictionary:dict];
        [sArr1 addObject:s];
    }
    NSMutableArray* sArr2 = [NSMutableArray array];
    for (int i=0; i<6; i++) {
        SRStudent* s = [SRStudent new];
        NSDictionary* dict = @{
            @"name" : @"xiaohei",
            @"age" : @(18+i),
            @"nick" : @"didi",
            @"length" : @(180 + 2*arc4random_uniform(5)),
        };
        [s setValuesForKeysWithDictionary:dict];
        [sArr2 addObject:s];
    }
    // 嵌套数组
    NSArray* nestArr = @[sArr1, sArr2];
    NSLog(@"nestArr : %@", nestArr);
    // 返回操作对象指定属性的集合
    NSArray* arr1 = [nestArr valueForKeyPath:@"@unionOfArrays.length"];
    NSLog(@"arr1 : %@", arr1);
    // 返回操作对象指定属性的集合 -- 去重
    NSArray* arr2 = [nestArr valueForKeyPath:@"@distinctUnionOfArrays.length"];
    NSLog(@"arr : %@", arr2);
}
    • 输出
    2020-06-23 13:47:02.717828+0800 001--KVC初探[9271:198128] arr1 : (
    184,
    184,
    188,
    180,
    182,
    186,
    182,
    180,
    188,
    180,
    188,
    180
)
2020-06-23 13:47:02.718036+0800 001--KVC初探[9271:198128] arr : (
    184,
    182,
    180,
    188,
    186
)
    • 测试代码
    - (void)setNesting {
    NSMutableSet* sSet1 = [NSMutableSet set];
    for (int i=0; i<6; i++) {
        SRStudent* s = [SRStudent new];
        NSDictionary* dict = @{
            @"name" : @"xiaoming",
            @"age" : @(18+i),
            @"nick" : @"dabai",
            @"length" : @(180 + 2*arc4random_uniform(5)),
        };
        [s setValuesForKeysWithDictionary:dict];
        [sSet1 addObject:s];
    }
    NSMutableSet* sSet2 = [NSMutableSet set];
    for (int i=0; i<6; i++) {
        SRStudent* s = [SRStudent new];
        NSDictionary* dict = @{
            @"name" : @"xiaohei",
            @"age" : @(18+i),
            @"nick" : @"didi",
            @"length" : @(180 + 2*arc4random_uniform(5)),
        };
        [s setValuesForKeysWithDictionary:dict];
        [sSet2 addObject:s];
    }
    NSLog(@"set1.length : %@", [sSet1 valueForKey:@"length"]);
    NSLog(@"set2.length : %@", [sSet2 valueForKey:@"length"]);
    // 嵌套数组
    NSSet* nestSet = [NSSet setWithObjects:sSet1, sSet2, nil];
    // 返回操作对象指定属性的集合 -- 并集
    NSArray* arr2 = [nestSet valueForKeyPath:@"@distinctUnionOfSets.length"];
    NSLog(@"arr : %@", arr2);
}
    • 输出
    2020-06-23 13:47:02.718341+0800 001--KVC初探[9271:198128] set1.length : {(
    182,
    188,
    184,
    186
)}
2020-06-23 13:47:02.718501+0800 001--KVC初探[9271:198128] set2.length : {(
    182,
    188,
    184,
    180
)}
2020-06-23 13:47:02.718725+0800 001--KVC初探[9271:198128] arr : {(
    182,
    188,
    184,
    180,
    186
)}

    3.6 array取值

    • 测试代码
    - (void)arrayGetValueDemo {
    SRStudent* student = [SRStudent new];
    student.penArr = [NSMutableArray arrayWithObjects:@"pen0", @"pen1", @"pen2", @"pen3", nil];
    // 这里有问题
//    NSArray* arr = [student valueForKey:@"pens"];
//    NSLog(@"pens : %@", arr);
    
    NSEnumerator* enumerator = [student.penArr objectEnumerator];
    NSString* str = nil;
    while (str = [enumerator nextObject]) {
        NSLog(@"str : %@", str);
    }
}
    • 输出
    2020-06-23 13:47:02.728408+0800 001--KVC初探[9271:198128] str : pen0
2020-06-23 13:47:02.728576+0800 001--KVC初探[9271:198128] str : pen1
2020-06-23 13:47:02.728682+0800 001--KVC初探[9271:198128] str : pen2
2020-06-23 13:47:02.728816+0800 001--KVC初探[9271:198128] str : pen3

    4. KVC : 访问非对象属性

    • 测试代码
    // 设置 值
ThreeFloats floats = {1., 2., 3.};
NSValue* value = [NSValue valueWithBytes:&floats objCType:@encode(ThreeFloats)];
[person setValue:value forKey:@"threeFloats"];
NSLog(@"%@", person);
// 取值
NSValue* result = [person valueForKey:@"threeFloats"];
NSLog(@"value : %@", result);
ThreeFloats retTh;
[result getValue:&retTh];
NSLog(@"th x:%f, y:%f, z:%f", retTh.x, retTh.y, retTh.z);
    • 输出
    [myName] : KVC_My_Name
[name] : KVC_Name
[array] : (
    120,
    2,
    3
)
[mArray] : (null)
[age] : 19
[threeFloats] : 1.000000, 2.000000, 3.000000
[student] : (null)
 value : {length = 12, bytes = 0x0000803f0000004000004040}
 th x:1.000000, y:2.000000, z:3.000000

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