对数组中的字典进行排序

原来字典
NSArray *arr = @[@{@"index" : @"3", @"key" : @"value"},
                 @{@"index" : @"4", @"key" : @"value"},
                 @{@"index" : @"1", @"key" : @"value"},
                 @{@"index" : @"2", @"key" : @"value"}];

要重新按照字典里的index值排序变成这样

NSArray *arr = @[@{@"index" : @"1", @"key" : @"value"},

                 @{@"index" : @"2", @"key" : @"value"},
                 @{@"index" : @"3", @"key" : @"value"},
                 @{@"index" : @"4", @"key" : @"value"}];

方法一：

- (NSComparisonResult)compare:(Person *)otherObject {
    return [self.birthDate compare:otherObject.birthDate];
}
NSArray *sortedArray;
sortedArray = [drinkDetails sortedArrayUsingSelector:@selector(compare:)];

方法二：（推荐）

NSSortDescriptor *sortDescriptor;
sortDescriptor = [[[NSSortDescriptor alloc] initWithKey:@"birthDate"
                                              ascending:YES] autorelease];
NSArray *sortDescriptors = [NSArray arrayWithObject:sortDescriptor];
NSArray *sortedArray;
sortedArray = [drinkDetails sortedArrayUsingDescriptors:sortDescriptors];


方法三：

NSArray *sortedArray;
sortedArray = [drinkDetails sortedArrayUsingComparator:^NSComparisonResult(id a, id b) {
    NSDate *first = [(Person*)a birthDate];
    NSDate *second = [(Person*)b birthDate];
    return [first compare:second];
}];