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65 lines
1.2 KiB
65 lines
1.2 KiB
5 years ago
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This check warns you when you have a custom setter for a weak property. When
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compiled with Automatic Reference Counting (ARC, `-fobj-arc`) ARC may set the
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property to `nil` without invoking the setter, for example:
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```objectivec
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#import <Foundation/Foundation.h>
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@interface Employee : NSObject {
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NSString* _name;
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__weak Employee* _manager;
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}
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-(id)initWithName:(NSString*)name;
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@property(atomic, weak) Employee* manager;
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-(void)report;
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@end
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@implementation Employee
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-(id)initWithName:(NSString*)name {
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_name = name;
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return self;
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}
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-(NSString*)description {
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return _name;
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}
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-(void)report {
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NSLog(@"I work for %@", _manager);
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}
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-(Employee*)manager {
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return _manager;
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}
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// DON'T do this; ARC will not call this when setting _manager to nil.
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-(void)setManager:(Employee*)newManager {
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NSLog(@"Meet the new boss...");
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_manager = newManager;
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}
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@end
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int main(int argc, char *argv[])
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{
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Employee* bob = [[Employee alloc] initWithName:@"Bob"];
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Employee* sue = [[Employee alloc] initWithName:@"Sue"];
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bob.manager = sue;
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[bob report];
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sue = nil;
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[bob report];
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return 0;
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}
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```
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This prints:
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```
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Meet the new boss...
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I work for Sue
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I work for (null)
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```
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Note that the custom setter was only invoked once.
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