爲NSDictionary中的所有現有密鑰設置相同的值

Question

在KVC中，我通常使用setValues:forKeyPath:爲集合中的對象設置相同的值。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"]) 

但是，對於字典，我們可以使用它嗎？現在我必須手動設置數值：

NSMutableDictionary *myDict; 
//... setupValues 
NSString *valueToSet = @"Hehe"; 
for (NSString *key in myDict) { 
    [myDict setObject:valueToSet forKey:key]; 
} 

是否有一個簡單的字典解決方案，如上例所示？

Answer 1

我不確定是否有一個函數（我猜沒有），但是如果你需要多次這樣做，你可以添加一個函數到NSMutableDictionary來幫助你：

@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，你將能夠做到這一點：

NSString *valueToSet = @"Hehe"; 
[myDict setAllKeysObject:valueToSet]; 

Answer 2

您可以使用allValues方法來獲取所有的值作爲NSArray第一。然後獲取數組的可變副本。最後，使用任何你在你的問題的可變數組中提到的KVC的方法（setValuesForKeysWithDictionary，setValue:forKeyPath:，等...）根據您的例子

[[[myDict allValues] mutableCopy] setValuesForKeysWithDictionary:@{@"stringProp" : @"Same same!"}];` 

[[[myDict allValues] mutableCopy] setValue:@"Another" forKeyPath:@"stringProp"];` 

---

或實施一類

@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 

，並利用它

[myDict setValuesForValuesWithKeysWithDictionary:@{@"stringProp" : @"Same same!"}]; 

[myDict setValue:@"Another" forValuesWithKeyPath:@"stringProp"]; 

---

這種方法有意義當你想使用KVC的辦法，是不可能接受的答案。

---

具體例

假設SomeClass定義如下

@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 

執行下面

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); 

將產生如下輸出

key1 = "someProperty=aaa, anotherProperty=111"; 
key2 = "someProperty=bbb, anotherProperty=222"; 
key3 = "someProperty=ccc, anotherProperty=333"; 

執行

[[[someDictionary allValues] mutableCopy] setValue:@"SameValue" forKeyPath:@"someProperty"]; 

NSLog(@"%@", someDictionary); 

後的輸出將

key1 = "someProperty=SameValue, anotherProperty=111"; 
key2 = "someProperty=SameValue, anotherProperty=222"; 
key3 = "someProperty=SameValue, anotherProperty=333";