Refactor custom animated image class

[dreampiggy]

Changes

The previous version (0.2.0), use a SDWebImageFLCoder custom coder, to create custom FLAnimatedImage for category. However, since it need extra config after import this plugin (not so out-of-box), and the associated object way of creating UIImage which represent FLAnimatedImage is not so convient. So this PR use another solution, by using Animated Image Customization.

Solution

This PR create a subclass of UIImage called SDFLAnimatedImage, and it conforms to SDAnimatedImage protocol. So our FLAnimatedImage+WebCache does not need any extra config, the wrapper class should be used to create and represent a actual FLAnimatedImage.

And it's now more easy to use, because you know that SDFLAnimatedImage is always GIF representation. So that it can be easy to detect and debug.

[dreampiggy]

This changes need to wait SDWebImage/SDWebImage#2453 to be merged in. So that we can keep the SDWebImageContextOptimalFrameCacheSize && SDWebImageContextPredrawingEnabled this usage. Or that this options will be un-available because the context options is not avaible for animated image class.

However, since this option are actually rare for most of usage, even that PR is not merged in, I think this solution is still better than the previous custom coder solution. Because now it don't need a extra coder, and make the SDFLAnimatedImage wrapper easy to use and determine than using a associated object. And it allows you to use it with the SDAnimatedImageView (Though it's not encouraged).

[bpoplauschi]

we don't want to add this, it will not work. Also breaks the CI

[dreampiggy]

@bpoplauschi It's local podfile because I test it locally to ensure it works. But that SDWebImage/SDWebImage#2453 (comment) was not been merged when this PR was created.

Now I can specify the branch dependency and update podfile.lock

[bpoplauschi]

Got it :)

[bpoplauschi]

Other than the Podfile change, looks good. Waiting for SDWebImage/SDWebImage#2453 to be merged

[bpoplauschi]

Waiting for CI

[dreampiggy]

Opps...The CI have a pod lib lint. Which will resolve the dependency and download the 5.0.0-beta2 code. Maybe I have to disable it temporally, only check the demo project build.

Later I will also move the test case into this repo.

[bpoplauschi]

Never mind. I can merge it as it is, it will work when we release a new version.