葛佳佳

@braebot Hi,could you give some property to change placeholder,e.g."MM / YY" -> "Month / Year",thank you.

We reproduced the problem: ``` Thread 14 name: Dispatch queue: com.onevcat.Kingfisher.Animator.preloadQueue Thread 14 Crashed: 0 CoreFoundation 0x18ef16a8c CFDataGetBytes + 148 1 ImageIO 0x193fbf964 CGImageGetImageSource + 156 2 ImageIO 0x193fbf964 CGImageGetImageSource...

Hi, @onevcat ,We reproduced the problem again