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Add protect when custom animated image class image data is nil during progressive animation check

This commit is contained in:
DreamPiggy 2018-08-30 23:20:35 +08:00
parent 1ed0b8cfe8
commit c76b9e3c2a
1 changed files with 4 additions and 0 deletions
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4
SDWebImage/SDAnimatedImageView.m
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@ -626,6 +626,10 @@ static NSUInteger SDDeviceFreeMemory() {
NSData *previousData = [((UIImage<SDAnimatedImage> *)previousImage) animatedImageData]; NSData *previousData = [((UIImage<SDAnimatedImage> *)previousImage) animatedImageData];
NSData *currentData = [((UIImage<SDAnimatedImage> *)image) animatedImageData]; NSData *currentData = [((UIImage<SDAnimatedImage> *)image) animatedImageData];
// Check whether to use progressive rendering or not // Check whether to use progressive rendering or not
if (!previousData || !currentData) {
// Early return
return;
}
// Warning: normally the `previousData` is same instance as `currentData` because our `SDAnimatedImage` class share the same `coder` instance internally. But there may be a race condition, that later retrived `currentData` is already been updated and it's not the same instance as `previousData`. // Warning: normally the `previousData` is same instance as `currentData` because our `SDAnimatedImage` class share the same `coder` instance internally. But there may be a race condition, that later retrived `currentData` is already been updated and it's not the same instance as `previousData`.
// And for protocol extensible design, we should not assume `SDAnimatedImage` protocol implementations always share same instance. So both of two reasons, we need that `rangeOfData` check. // And for protocol extensible design, we should not assume `SDAnimatedImage` protocol implementations always share same instance. So both of two reasons, we need that `rangeOfData` check.