Fix StorageUI Bug and Update demo usage for SDWebImgae integration

[dreampiggy]

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Fix issues related StorageUI and SDWebImage, introduced in #841


1. The FIRStorage throw exception on passed url contains object path
2. The progress block may been called on main queue, should use another coder queue for decoding
3. The expectedSize should use URLResponse's info to check, but not the bodyLength

CC @morganchen12

[morganchen12]

It looks like a new coderQueue is allocated on each invocation of this method, but never retained anywhere. Is this intentional?

[dreampiggy]

It looks like a new coderQueue is allocated on each invocation of this method, but never retained anywhere.

It retained in the below, the dataWithMaxSize:completion: block, here use coderQueue addOperationWithBlock:. And also, the progressive one. The block keep a strong reference to capture Objecitve-C object by default (unless you mark __weak).

Just use NSOperation to replace previous's GCD.

[dreampiggy]

The NSOperationQueue lifetime is associated to the completion block, and the completion block lifetime is associated to FIRStorageDownloadTask. This implements the design I want : Each download task use independent serial coder queue

[morganchen12]

Sounds good.

[dreampiggy]

Or, if you think it's hard to find, we can change this into an associated object of FIRStorageDownloadTask, like

@interface FIRStorageDownloadTask (StorageUI)
@property (nonatomic) NSOperationQueue *coderQueue;
@end
@implementation FIRStorageDownloadTask (StorageUI)
- (NSOperationQueue *)coderQueue {
    NSOperationQueue *coderQueue = objc_getAsscoaitedObject(self, @selector(coderQueue));
    if (!coderQueue) {
        coderQueue = [NSOperationQueue new];
        coderQueue.maxConcurrentOperationCount = 1;
        objc_setAssociatedObject(self, @selector(coderQueue), coderQueue, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    } 
    return coderQueue;
}
@end

But actually, they have the same effect...

[morganchen12]

I'm ok with the way the code is, just wanted to clarify 👍

[morganchen12]

LGTM, thanks @dreampiggy!

[dreampiggy]

If you find there are no extra review suggestion to check, feel free to merge. :)

[dreampiggy]

The Travis-CI failed bacause of CocoaPods repo update failed :(

@morganchen12 Can you update the Gemfile and CI to use new CocoaPods version ? At least v1.8.0, which introduce the CDN trunk instead of Spec repo. Which don't need to wasting time to git clone the https://github.com/CocoaPods/Specs. It use a CDN for HTTP download, 10x faster.

[morganchen12]

Updated gems in #844.

[morganchen12]

The changes look fine to me, I'll take care of fixing the build. Thanks @dreampiggy!