Get the current first responder without using a private API

Question

I submitted my app a little over a week ago and got the dreaded rejection email today. It tells me that my app cannot be accepted because I\'m using a non-public API; specif

Answer 1

Here's a solution which reports the correct first responder (many other solutions won't report a UIViewController as the first responder, for example), doesn't require looping over the view hierarchy, and doesn't use private APIs.

It leverages Apple's method sendAction:to:from:forEvent:, which already knows how to access the first responder.

We just need to tweak it in 2 ways:

• Extend UIResponder so it can execute our own code on the first responder.
• Subclass UIEvent in order to return the first responder.

Here is the code:

@interface ABCFirstResponderEvent : UIEvent
@property (nonatomic, strong) UIResponder *firstResponder;
@end

@implementation ABCFirstResponderEvent
@end

@implementation UIResponder (ABCFirstResponder)
- (void)abc_findFirstResponder:(id)sender event:(ABCFirstResponderEvent *)event {
    event.firstResponder = self;
}
@end

@implementation ViewController

+ (UIResponder *)firstResponder {
    ABCFirstResponderEvent *event = [ABCFirstResponderEvent new];
    [[UIApplication sharedApplication] sendAction:@selector(abc_findFirstResponder:event:) to:nil from:nil forEvent:event];
    return event.firstResponder;
}

@end