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/*
* Copyright (c) Facebook, Inc. and its affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
#import <Foundation/NSObject.h>
@protocol BarDelegate<NSObject>
@optional
- (void)optionalFunction;
@end
@interface Bar : NSObject
@property(weak, nonatomic) id<BarDelegate> delegate;
- (void)action;
@end
@implementation Bar
- (void)unsafeAction {
[self.delegate optionalFunction];
}
- (void)safeAction {
id<BarDelegate> delegate = self.delegate;
if ([delegate respondsToSelector:@selector(optionalFunction)]) {
[self.delegate optionalFunction];
}
}
@end
@interface Foo : NSObject<BarDelegate>
- (void)doSomething;
@end
@implementation Foo
- (void)doSomething {
Bar* x = [Bar new];
x.delegate = self;
[x unsafeAction];
}
@end
int main(int argc, const char* argv[]) {
Foo* y = [Foo new];
[y doSomething];
return 0;
}