参考 https://www.jianshu.com/p/4748ef75126a
Key
/**
* @public 可以在任何地方访问
* @protected 可以在当前类和其子类里访问
* @private 只能在当前类里访问
*/
@interface Teacher : NSObject
{
@private
int _age;
}
@property (nonatomic, strong, readonly) NSString *name;
@property (nonatomic, assign, getter = isMale) BOOL male;
/**
* 打印
*/
- (void)log;
@end
Teacher *teacher = [Teacher new];
//age是私有private变量和name是只读readonly变量
//teacher.age;
//teacher.name = @"haha";
[teacher log];
[teacher setValue:@"Jack" forKey:@"name"];
[teacher setValue:@24 forKey:@"age"];
[teacher setValue:@1 forKey:@"male"];
[teacher log];
NSLog(@"name: %@", [teacher valueForKey:@"name"]);
NSLog(@"age: %d", [[teacher valueForKey:@"age"] intValue]);
NSLog(@"male: %d", [[teacher valueForKey:@"male"] boolValue]);
KeyPath(对象包含了其他对象)
@class Student;
@interface Teacher : NSObject
@property (nonatomic, strong) Student *student;
@end
@interface Student : NSObject
{
@private
NSString *_name;
}
- (void)log;
@end
Teacher *teacher = [Teacher new];
Student *student = [Student new];
[student log];
[student setValue:@"Kobe" forKey:@"name"];
[teacher setValue:student forKey:@"student"];
NSString *studentName = [teacher valueForKeyPath:@"student.name"];
NSLog(@"Student name: %@",studentName);
[teacher setValue:@"James" forKeyPath:@"student.name"];
[student log];
/*
如果你不小心错误的使用了key而非keyPath的话，KVC会直接查找
student.name这个属性，很明显，这个属性并不存在。所以会再调用
UndefinedKey相关方法。而KVC对于keyPath是搜索机制第一步就是分离
key，用小数点.来分割key，然后再像普通key一样按照先前介绍的顺序搜
索下去。如果没有小数点，就直接向普通key来搜索。
*/
集合
@class Student;
@interface Teacher : NSObject
@property (nonatomic, strong) Student *student;
- (instancetype)initWithStudent:(Student *)student;
@end
@class Book;
@interface Student : NSObject
@property (nonatomic, strong) NSArray<Book *> *bookList;
- (instancetype)initWithBookList:(NSArray *)bookList;
@end
@interface Book : NSObject
@property (nonatomic, copy) NSString *name;
@property (nonatomic, assign) float price;
- (instancetype)initWithName:(NSString *)name price:(float)price;
@end
teacher 有property student
student 有NSArray<Book *> *bookList
NSMutableArray *bookList = [NSMutableArray array];
for(int i = 0; i <= 10; i++)
{
Book *book = [[Book alloc] initWithName:[NSString stringWithFormat:@"book%d",i] price:i*10];
[bookList addObject:book];
}
Student *student = [[Student alloc] initWithBookList:bookList];
Teacher *teacher = [[Teacher alloc] initWithStudent:student];
for(Book *book in [student valueForKey:@"bookList"])
{
NSLog(@"bookName:%@ \t price:%f", book.name, book.price);
}
NSLog(@"All book name: %@", [teacher valueForKeyPath:@"student.bookList.name"]);
NSLog(@"All book name: %@", [student valueForKeyPath:@"bookList.name"]);
NSLog(@"All book price: %@", [teacher valueForKeyPath:@"student.bookList.price"]);
NSLog(@"All book price: %@", [student valueForKeyPath:@"bookList.price"]);
NSLog(@"count of book price: %@",[student valueForKeyPath:@"bookList.@count.price"]);
NSLog(@"min of book price: %@",[student valueForKeyPath:@"bookList.@min.price"]);
NSLog(@"max of book price: %@",[student valueForKeyPath:@"bookList.@max.price"]);
NSLog(@"sum of book price: %@",[student valueForKeyPath:@"bookList.@sum.price"]);
NSLog(@"avg of book price: %@",[student valueForKeyPath:@"bookList.@avg.price"]);
字典
{
"product":
{
"name": "手机",
"categoryList": [
{
"name": "iPhone",
"id": "1",
"price": "100.03",
"image": "www.iPhone.com"
},
{
"name": "三星",
"id": "2",
"price": "80",
"image": "www.samsung.com"
},
{
"name": "小米",
"id": "3",
"price": "60",
"image": "www.xiaomi.com"
},
{
"name": "华为",
"id": "4",
"price": "40.5",
"image": "www.huawei.com"
}
]
}
}
@interface CategoryList : NSObject
@property (nonatomic, copy) NSString *name;
@property (nonatomic, copy) NSString *image;
@property (nonatomic, copy) NSString *productId;
@property (nonatomic, assign) float price;
- (instancetype)initWithDictionary:(NSDictionary *)dictionary;
@end
@implementation CategoryList
- (instancetype)initWithDictionary:(NSDictionary *)dictionary
{
if(self = [super init])
{
[self setValuesForKeysWithDictionary:dictionary];
}
return self;
}
- (void)setValue:(id)value forKey:(NSString *)key
{
//key为"price" （"price": "100.03"） value为字符串 price为float
if([key isEqualToString:@"price"])
{
self.price = [value floatValue];
}
else
{
[super setValue:value forKey:key];
}
}
- (void)setValue:(id)value forUndefinedKey:(NSString *)key
{
//key为"id" （"id": "1"） value为字符串 赋值给productId
if([key isEqualToString:@"id"])
{
self.productId = value;
}
else
{
[super setValue:value forUndefinedKey:key];
}
}
@end
@interface Product : NSObject
@property (nonatomic, copy) NSString *name;
@property (nonatomic, strong) NSMutableArray *categoryList;
- (instancetype)initWithDictionary:(NSDictionary *)dictionary;
@end
- (instancetype)initWithDictionary:(NSDictionary *)dictionary
{
if(self = [super init])
{
[self setValuesForKeysWithDictionary:dictionary];
}
return self;
}
- (void)setValue:(id)value forKey:(NSString *)key
{
//key为categoryList value是数组 数组里每个值是字典
if([key isEqualToString:@"categoryList"])
{
self.categoryList = [NSMutableArray array];
for(NSMutableDictionary *dict in value)
{
CategoryList *list = [[CategoryList alloc] initWithDictionary:dict];
[self.categoryList addObject:list];
}
}
else
{
[super setValue:value forKey:key];
}
}
NSString *path = [[NSBundle mainBundle] pathForResource:@"product" ofType:@"json"];
NSData *data = [NSData dataWithContentsOfFile:path];
NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:nil];
NSLog(@"%@", dict);
NSDictionary *dataDict = dict[@"product"];
Product *p = [[Product alloc] initWithDictionary:dataDict];
NSLog(@"%@ %@", p.name, p.categoryList);
for(CategoryList *list in p.categoryList)
{
NSLog(@"%@ == %@ == %@ == %.2f", list.name, list.image, list.productId, list.price);
}
修改属性
//在iOS6.0之前 可以通过KVC来设置_placeholderLabel的属性值
[_textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];
[_textField setValue:[UIFont systemFontOfSize:16] forKeyPath:@"_placeholderLabel.font"];
//iOS 6.0之后 提供的attributedPlaceholder属性
NSString *holderText = @"输入密码";
NSMutableAttributedString *placeholder = [[NSMutableAttributedString alloc] initWithString:holderText];
[placeholder addAttribute:NSForegroundColorAttributeName
value:[UIColor redColor]
range:NSMakeRange(0, holderText.length)];
[placeholder addAttribute:NSFontAttributeName
value:[UIFont boldSystemFontOfSize:16]
range:NSMakeRange(0, holderText.length)];
_textField.attributedPlaceholder = placeholder;
[_pageControl setValue:[UIImage imageNamed:@"selected"] forKey:@"_currentPageImage"];
[_pageControl setValue:[UIImage imageNamed:@"unselected"] forKey:@"_pageImage"];
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