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Nic Huang
Courses Plus Student 10,573 PointsBlock and self cause retain cycle
I was told block would cause retain cycle when you use self in block like this:
self.onCompleteBlock = ^{
[self doSomething];
}
[[SSDHTTPClient sharedInstance] login:parameters completion:^(BOOL success, NSURLSessionDataTask *task, id responseObject) {
if (success) {
NSString *string = [[NSString alloc]initWithData:responseObject encoding:NSUTF8StringEncoding];
NSDictionary *dict = [self splitString: string];
self.userID = dict[@"userID"];
self.subscriberID = dict[@"subscriberID"];
[self writeUserIDIntoUserDefault:self.userID withSubscriberID:self.subscriberID];
But I want to know if I use block this way, does it cause retain cycle too? Because when I profiled this code in instrument, it doesn't show any leak. And in Xcode, the viewController's dealloc is also properly get called.
1 Answer
Thomas Nilsen
14,957 PointsIt's not correct to say it will cause a retain cycle, but it CAN. You can avoid it by doing something like this:
__typeof(self) __weak weakSelf = self;
self.onCompleteBlock = ^{
[weakSelf doSomething];
}