Add fallback condition when adding a protocol to a subclass

[L1ghtmann]

What does this implement/fix? Explain your changes.

• Implements a fallback to objc_getProtocol in %subclass as proposed by RPetrich in %subclass with protocols crashes in the constructor #9 (comment)

Does this close any currently open issues?

Appears to resolve #9

Any relevant logs, error output, etc?

N/A

Any other comments?

With the following code (a modified version of the code mentioned in the issue above):

@protocol CCSectionDelegate <NSObject>
- (void)updateStatusText:(NSString *)text;
- (void)requestControlCenterDismissal;
- (void)sectionHeightChanged;
- (void)showViewController:(UIViewController *)vc animated:(BOOL)animated completion:(void (^)(void))completion;
@end

%subclass CCSectionViewController : SpringBoard <CCSectionDelegate, UICollectionViewDelegate>
%end

Current logos: crash
This branch: no crash

Where has this been tested?

Operating System: …

Linux (WSL)
iP7 -- iOS 14.3 - unc0ver

Platform: …

Target Platform: …

Toolchain Version: …

SDK Version: …

[uroboro]

If you use the "elvis" operator, you can reduce the number of calls to objc_getProtocol():

objc_getProtocol(\"$_\") ?: \@protocol($_)

[L1ghtmann]

If you use the "elvis" operator, you can reduce the number of calls to objc_getProtocol():

objc_getProtocol(\"$_\") ?: \@protocol($_)

Today I learned that's a thing. Thanks!

[L1ghtmann]

It appears this exact fix has been proposed on two separate occasions and both times Dustin pointed out potential problems that would need to be addressed:

• Refer to protocols with @protocol theos#115 (comment)
• Fix %subclass Protocol Issue theos#201 (comment)