UIActivityViewControllerでTwitterの時だけハッシュタグを追加する

ActivityText.h

#import <Foundation/Foundation.h>

@interface ActivityText : NSObject  <UIActivityItemSource>

-(id)initWithText:(NSString *)text hashTag:(NSString *)hashTag;

@end

ActivityText.m

#import "ActivityText.h"

@implementation ActivityText
{
    NSString *_text, *_hashTag;
}

-(id)initWithText:(NSString *)text hashTag:(NSString *)hashTag
{
    self = [super init];
    if (self) {
        _text = text;
        _hashTag = hashTag;
    }
    return self;
}

#pragma mark - UIActivityItemSource

-(id)activityViewController:(UIActivityViewController *)activityViewController itemForActivityType:(NSString *)activityType
{
    // Twitterの時だけハッシュタグをつける
    if ([activityType isEqualToString:UIActivityTypePostToTwitter]) {
        return [NSString stringWithFormat:@"%@ #%@", _text, _hashTag];
    }
    return _text;
}

-(id)activityViewControllerPlaceholderItem:(UIActivityViewController *)activityViewController
{
    return _text;
}

@end