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