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Merge pull request #1624 from maicki/FixDelegateProxyCrash

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[Accessibility / iOS 8] Fix 8.0 and 8.1-only, VoiceOver crash when clearing delegate / dataSource for Table or Collection
This commit is contained in:
appleguy 2016-05-10 13:43:40 -07:00
commit d88e170163
3 changed files with 22 additions and 23 deletions
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18
AsyncDisplayKit/ASCollectionView.mm
View File

@ -343,10 +343,10 @@ static NSString * const kCellReuseIdentifier = @"_ASCollectionViewCell";
{
// Note: It's common to check if the value hasn't changed and short-circuit but we aren't doing that here to handle
// the (common) case of nilling the asyncDataSource in the ViewController's dealloc. In this case our _asyncDataSource
// will return as nil (ARC magic) even though the _proxyDataSource still exists. It's really important to nil out
// super.dataSource in this case because calls to ASCollectionViewProxy will start failing and cause crashes.
super.dataSource = nil;
// will return as nil (ARC magic) even though the _proxyDataSource still exists. It's really important to hold a strong
// reference to the old dataSource in this case because calls to ASCollectionViewProxy will start failing and cause crashes.
NS_VALID_UNTIL_END_OF_SCOPE id oldDataSource = super.dataSource;
if (asyncDataSource == nil) {
_asyncDataSource = nil;
_proxyDataSource = _isDeallocating ? nil : [[ASCollectionViewProxy alloc] initWithTarget:nil interceptor:self];
@ -375,13 +375,9 @@ static NSString * const kCellReuseIdentifier = @"_ASCollectionViewCell";
{
// Note: It's common to check if the value hasn't changed and short-circuit but we aren't doing that here to handle
// the (common) case of nilling the asyncDelegate in the ViewController's dealloc. In this case our _asyncDelegate
// will return as nil (ARC magic) even though the _proxyDelegate still exists. It's really important to nil out
// super.delegate in this case because calls to ASCollectionViewProxy will start failing and cause crashes.
// Order is important here, the asyncDelegate must be callable while nilling super.delegate to avoid random crashes
// in UIScrollViewAccessibility.
super.delegate = nil;
// will return as nil (ARC magic) even though the _proxyDataSource still exists. It's really important to hold a strong
// reference to the old delegate in this case because calls to ASCollectionViewProxy will start failing and cause crashes.
NS_VALID_UNTIL_END_OF_SCOPE id oldDelegate = super.delegate;
if (asyncDelegate == nil) {
_asyncDelegate = nil;

17
AsyncDisplayKit/ASTableView.mm
View File

@ -268,10 +268,9 @@ static NSString * const kCellReuseIdentifier = @"_ASTableViewCell";
{
// Note: It's common to check if the value hasn't changed and short-circuit but we aren't doing that here to handle
// the (common) case of nilling the asyncDataSource in the ViewController's dealloc. In this case our _asyncDataSource
// will return as nil (ARC magic) even though the _proxyDataSource still exists. It's really important to nil out
// super.dataSource in this case because calls to ASTableViewProxy will start failing and cause crashes.
super.dataSource = nil;
// will return as nil (ARC magic) even though the _proxyDataSource still exists. It's really important to hold a strong
// reference to the old dataSource in this case because calls to ASTableViewProxy will start failing and cause crashes.
NS_VALID_UNTIL_END_OF_SCOPE id oldDataSource = self.dataSource;
if (asyncDataSource == nil) {
_asyncDataSource = nil;
@ -299,13 +298,9 @@ static NSString * const kCellReuseIdentifier = @"_ASTableViewCell";
{
// Note: It's common to check if the value hasn't changed and short-circuit but we aren't doing that here to handle
// the (common) case of nilling the asyncDelegate in the ViewController's dealloc. In this case our _asyncDelegate
// will return as nil (ARC magic) even though the _proxyDelegate still exists. It's really important to nil out
// super.delegate in this case because calls to ASTableViewProxy will start failing and cause crashes.
// Order is important here, the asyncDelegate must be callable while nilling super.delegate to avoid random crashes
// in UIScrollViewAccessibility.
super.delegate = nil;
// will return as nil (ARC magic) even though the _proxyDataSource still exists. It's really important to hold a strong
// reference to the old delegate in this case because calls to ASTableViewProxy will start failing and cause crashes.
NS_VALID_UNTIL_END_OF_SCOPE id oldDelegate = super.delegate;
if (asyncDelegate == nil) {
_asyncDelegate = nil;

10
AsyncDisplayKit/Details/ASDelegateProxy.m
View File

@ -125,7 +125,15 @@
if (_target) {
return [_target respondsToSelector:aSelector] ? _target : nil;
} else {
[_interceptor proxyTargetHasDeallocated:self];
// The _interceptor needs to be nilled out in this scenario. For that a strong reference needs to be created
// to be able to nil out the _interceptor but still let it know that the proxy target has deallocated
// We have to hold a strong reference to the interceptor as we have to nil it out and call the proxyTargetHasDeallocated
// The reason that the interceptor needs to be nilled out is that there maybe a change of a infinite loop, for example
// if a method will be called in the proxyTargetHasDeallocated: that again would trigger a whole new forwarding cycle
id <ASDelegateProxyInterceptor> interceptor = _interceptor;
_interceptor = nil;
[interceptor proxyTargetHasDeallocated:self];
return nil;
}
}