ios - Unable to edit screenshots, performChanges block fails -

i'm developing app allows users edit photos using photokit. saving edited photo disk jpeg. avoid converting jpeg , have implemented modifications in order that. works great photos taken camera, if try edit screenshot, phphotolibrary.sharedphotolibrary().performchanges block fail , log the operation couldn’t completed. (cocoa error -1.). not sure why causing performchanges block fail, have done wrong here?

i've created sample app available download demonstrates problem, , i've included relevant code below. app attempts edit newest photo in photo library. if succeeds prompt access edit photo, otherwise nothing happen , you'll see console log. reproduce issue, take screenshot run app.

current code works screenshots:

let jpegdata: nsdata = outputphoto.jpegrepresentationwithcompressionquality(0.9)  let contenteditingoutput = phcontenteditingoutput(contenteditinginput: self.input)  var error: nserror? let success = jpegdata.writetourl(contenteditingoutput.renderedcontenturl, options: nsdatawritingoptions.atomicwrite, error: &error) if success {     return contenteditingoutput } else {     return nil } 

replacement code causes screenshots fail:

let url = self.input.fullsizeimageurl let orientation = self.input.fullsizeimageorientation var inputimage = ciimage(contentsofurl: url) inputimage = inputimage.imagebyapplyingorientation(orientation)  let outputphoto = createoutputimagefrominputimage(inputimage)!  let originalimagedata = nsdata(contentsofurl: self.input.fullsizeimageurl)! let imagesource = cgimagesourcecreatewithdata(originalimagedata, nil)  let dataref = cfdatacreatemutable(nil, 0) let destination = cgimagedestinationcreatewithdata(dataref, cgimagesourcegettype(imagesource), 1, nil) //gettype automatically selects jpg, png, etc based on original format  struct contextstruct {     static var cicontext: cicontext? = nil } if contextstruct.cicontext == nil {     let eaglcontext = eaglcontext(api: .opengles2)     contextstruct.cicontext = cicontext(eaglcontext: eaglcontext) }  let cgimage = contextstruct.cicontext!.createcgimage(outputphoto, fromrect: outputphoto.extent())  cgimagedestinationaddimage(destination, cgimage, nil)  if cgimagedestinationfinalize(destination) {      let contenteditingoutput = phcontenteditingoutput(contenteditinginput: self.input)       var error: nserror?      let imagedata: nsdata = dataref      let success = imagedata.writetourl(contenteditingoutput.renderedcontenturl, options: .atomicwrite, error: &error)      if success {           //it succeed           return contenteditingoutput      } else {           return nil      } } 

the problem happens due fact adjusted photos saved jpg files, , screenshots in fact png files.

it occurred me while debugging sample project , saw in photoeditor, contenteditingoutput.renderedcontenturl url jpg, while if examine result of cgimagesourcegettype(imagesource) clear it's png (returns png uti: public.png).

so went , read documentation renderedcontenturl states if editing photo asset, altered image written in jpeg format - won't work if image png. leads me think apple don't support editing png files or don't want to. go figure..