Objective c 为NSDictionary中的所有现有键设置相同的值
在KVC中,我通常使用Objective c 为NSDictionary中的所有现有键设置相同的值,objective-c,cocoa,nsmutabledictionary,kvc,Objective C,Cocoa,Nsmutabledictionary,Kvc,在KVC中,我通常使用setValues:forKeyPath:为集合中的对象设置相同的值。例如: NSMutableArray <SomeClass *> *arr = [[NSMutableArray alloc] initWithCapacity:10]; for (int i = 0; i < 10; i++) { SomeClass *obj = [[SomeClass alloc] init]; obj.stringProp = @(i).strin
setValues:forKeyPath:
为集合中的对象设置相同的值。例如:
NSMutableArray <SomeClass *> *arr = [[NSMutableArray alloc] initWithCapacity:10];
for (int i = 0; i < 10; i++) {
SomeClass *obj = [[SomeClass alloc] init];
obj.stringProp = @(i).stringValue;
[arr addObject:obj];
}
NSLog(@"- %@", [arr valueForKeyPath:@"stringProp"]);
[arr setValuesForKeysWithDictionary:@{@"stringProp" : @"Same same!"}];
NSLog(@"- %@", [arr valueForKeyPath:@"stringProp"]);
[arr setValue:@"Another" forKeyPath:@"stringProp"];
NSLog(@"- %@", [arr valueForKeyPath:@"stringProp"])
是否有一个简单的字典解决方案,如上面的示例?我不确定是否有一个函数(我想没有),但如果您需要多次这样做,您可以向NSMutableDictionary添加一个函数来帮助您:
@interface NSMutableDictionary (NSMutableDictionarySetAllKeysObject)
-(void)setAllKeysObject:(nonnull id)object;
@end
@implementation NSMutableDictionary (NSMutableDictionarySetAllKeysObject)
-(void)setAllKeysObject:(nonnull id)object
{
for (NSString *key in self.allKeys) {
[self setObject:object forKey:key];
}
}
@end
所以你可以这样做:
NSString *valueToSet = @"Hehe";
[myDict setAllKeysObject:valueToSet];
您可以使用
allValues
方法首先将所有值作为NSArray
获取。然后获取数组的可变副本。最后,在可变数组上使用问题中提到的任何KVC方法(setValuesForKeysWithDictionary
,setValue:forKeyPath:
,等等)
根据你的例子
[[[myDict allValues] mutableCopy] setValuesForKeysWithDictionary:@{@"stringProp" : @"Same same!"}];`
[[[myDict allValues] mutableCopy] setValue:@"Another" forKeyPath:@"stringProp"];`
或者实现一个类别
@interface NSMutableDictionary (KVCForValues)
- (void)setValuesForValuesWithKeysWithDictionary:(NSDictionary<NSString *, id> *)keyedValues;
- (void)setValue:(nullable id)value forValuesWithKeyPath:(NSString *)keyPath;
@end
@implementation NSMutableDictionary (KVCForValues)
- (void)setValuesForValuesWithKeysWithDictionary:(NSDictionary<NSString *,id> *)keyedValues {
[[[self allValues] mutableCopy] setValuesForKeysWithDictionary:keyedValues];
}
- (void)setValue:(id)value forValuesWithKeyPath:(NSString *)keyPath {
[[[self allValues] mutableCopy] setValue:value forKeyPath:keyPath];
}
@end
当您想要使用KVC方法时,这种方法是有意义的,因为在接受的答案中不可能使用KVC方法
具体例子 假设
SomeClass
定义如下
@interface SomeClass: NSObject
@property (nonatomic, strong) NSString *someProperty;
@property (nonatomic, assign) NSInteger anotherProperty;
@end
@implementation SomeClass
- (NSString *)description {
return [NSString stringWithFormat:@"someProperty=%@, anotherProperty=%d", self.someProperty, (int)self.anotherProperty];
}
@end
执行以下命令
SomeClass *value1 = [[SomeClass alloc] init];
value1.someProperty = @"aaa";
value1.anotherProperty = 111;
SomeClass *value2 = [[SomeClass alloc] init];
value2.someProperty = @"bbb";
value2.anotherProperty = 222;
SomeClass *value3 = [[SomeClass alloc] init];
value3.someProperty = @"ccc";
value3.anotherProperty = 333;
NSDictionary *someDictionary = @{@"key1": value1, @"key2": value2, @"key3": value3};
NSLog(@"%@", someDictionary);
将产生以下输出
key1 = "someProperty=aaa, anotherProperty=111";
key2 = "someProperty=bbb, anotherProperty=222";
key3 = "someProperty=ccc, anotherProperty=333";
执行后
[[[someDictionary allValues] mutableCopy] setValue:@"SameValue" forKeyPath:@"someProperty"];
NSLog(@"%@", someDictionary);
输出将是
key1 = "someProperty=SameValue, anotherProperty=111";
key2 = "someProperty=SameValue, anotherProperty=222";
key3 = "someProperty=SameValue, anotherProperty=333";
可能它们还没有这方面的功能。我会在几天内接受你的回答,以防有人找到我想要的方法:pIt似乎你误解了这个问题。在我的示例中(对于
NSDictionary
),我询问是否可以使用KVC为平面字典中的所有键设置一个值。比如,一个带有键和值的Dict:[0:“0”,1:“1”,2:“2”,3:“3”]
,我想让它[0:“相同”,1:“相同”,2:“相同”,3:“相同”]
。这对你有意义吗?@Eddie上面的代码就是这么做的。我添加了一个示例代码。在任何情况下,注释中NSDictionary的值都应该是问题中的类型SomeClass
,而不是NSString
。即使使用NSMutableArray
,它也不适用于NSString
。这是一个很好的解释。但是,不可能直接为键设置值,而是需要对象作为桥接,并为对象的属性设置值,对吗?比如,不可能像我之前的评论那样设置它,是吗?@Eddie不可能
[[[someDictionary allValues] mutableCopy] setValue:@"SameValue" forKeyPath:@"someProperty"];
NSLog(@"%@", someDictionary);
key1 = "someProperty=SameValue, anotherProperty=111";
key2 = "someProperty=SameValue, anotherProperty=222";
key3 = "someProperty=SameValue, anotherProperty=333";