Twitter doesn't allow setting text in TWTRConposerViewControlller, which is used for app cards. This is a simple hack to do just that.

CMTWTRConposerViewControlller.h

//
//  CMTWTRConposerViewControlller.h
//  ProtoSketch
//
//  Created by Robert Dimitrov on 5/13/16.
//  Copyright © 2016 Codemotion Ltd. All rights reserved.
//

#import <TwitterKit/TwitterKit.h>

@interface CMTWTRConposerViewControlller : TWTRComposerViewController

@property (nonatomic, readwrite, copy) NSString *tweetText;

@end

CMTWTRConposerViewControlller.m

//
//  CMTWTRConposerViewControlller.m
//  ProtoSketch
//
//  Created by Robert Dimitrov on 5/13/16.
//  Copyright © 2016 Codemotion Ltd. All rights reserved.
//

#import "CMTWTRConposerViewControlller.h"

@implementation CMTWTRConposerViewControlller

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    
    for (UIView *subview in self.view.subviews) {
        if ([subview respondsToSelector:@selector(textView)]) {
            UITextView *textView = (UITextView *)[subview performSelector:@selector(textView)];
            if ([textView isKindOfClass:[UITextView class]]) {
                textView.text = self.tweetText;
                break;
            }
        }
    }
}

@end