将NSArray转换为NSDictionary

我如何将NSArray转换为NSDictionary ，使用数组对象的int字段作为NSDictionary键？

Answer 1

 - (NSDictionary *) indexKeyedDictionaryFromArray:(NSArray *)array { id objectInstance; NSUInteger indexKey = 0U; NSMutableDictionary *mutableDictionary = [[NSMutableDictionary alloc] init]; for (objectInstance in array) [mutableDictionary setObject:objectInstance forKey:[NSNumber numberWithUnsignedInt:indexKey++]]; return (NSDictionary *)[mutableDictionary autorelease]; } 

Answer 2

试试这个魔法：

 NSDictionary *dict = [NSDictionary dictionaryWithObjects:records forKeys:[records valueForKey:@"intField"]]; 

仅供参考，这是可能的，因为这个内置function：

 @interface NSArray(NSKeyValueCoding) /* Return an array containing the results of invoking -valueForKey: on each of the receiver's elements. The returned array will contain NSNull elements for each instance of -valueForKey: returning nil. */ - (id)valueForKey:(NSString *)key; 

Answer 3

这为NSArray添加了一个类别扩展。 需要C99模式（这是目前的默认，但以防万一）。

在.h文件的某处可以#import所有..

 @interface NSArray (indexKeyedDictionaryExtension) - (NSDictionary *)indexKeyedDictionary @end 

在.m文件中

 @implementation NSArray (indexKeyedDictionaryExtension) - (NSDictionary *)indexKeyedDictionary { NSUInteger arrayCount = [self count]; id arrayObjects[arrayCount], objectKeys[arrayCount]; [self getObjects:arrayObjects range:NSMakeRange(0UL, arrayCount)]; for(NSUInteger index = 0UL; index < arrayCount; index++) { objectKeys[index] = [NSNumber numberWithUnsignedInteger:index]; } return([NSDictionary dictionaryWithObjects:arrayObjects forKeys:objectKeys count:arrayCount]); } @end 

使用示例：

 NSArray *array = [NSArray arrayWithObjects:@"zero", @"one", @"two", NULL]; NSDictionary *dictionary = [array indexKeyedDictionary]; NSLog(@"dictionary: %@", dictionary); 

输出：

 2009-09-12 08:41:53.128 test[66757:903] dictionary: { 0 = zero; 1 = one; 2 = two; } 

Answer 4

这是从员工列表NSMutableArray创buildNSMutableDictionary一个例子：

  NSMutableArray *emloyees = [[NSMutableArray alloc]initWithObjects:@"saman",@"Ruchira",@"Rukshan",@"ishan",@"Harsha",@"Ghihan",@"Lakmali",@"Dasuni", nil]; NSMutableDictionary *dict = [NSMutableDictionary dictionary]; for (NSString *word in emloyees) { NSString *firstLetter = [[word substringToIndex:1] uppercaseString]; letterList = [dict objectForKey:firstLetter]; if (!letterList) { letterList = [NSMutableArray array]; [dict setObject:letterList forKey:firstLetter]; } [letterList addObject:word];} NSLog(@"dic %@",dict); 

Answer 5

 - (NSDictionary *) indexKeyedDictionaryFromArray:(NSArray *)array { NSMutableDictionary *mutableDictionary = [[NSMutableDictionary alloc] init]; [array enumerateObjectsUsingBlock: ^(id obj, NSUInteger idx, BOOL *stop){ NSNumber *index = [NSNumber numberWithInteger:idx]; [mutableDictionary setObject:obj forKey:index]; }]; NSDictionary *result = [NSDictionary.alloc initWithDictionary:mutableDictionary]; return result; } 

Answer 6

我已经创build了一个简单的库，称为Linq到ObjectiveC ，这是一个方法的集合，使得这种问题更容易解决。 在你的情况下，你需要Linq-to-ObjectiveC的toDictionary方法，其中你的'int'字段是通过一个关键select器指定的：

 NSDictionary* dictionary = [sourceArray toDictionaryWithKeySelector:^id(id item) { return [item intField]; }]; 

这将返回一个字典，其中的键由源数组中的intField给出。