ios - App crashes after receiving memory warning due to images loading -


i developing first app user can save 13 screenshots , swipe between in 1 view controller (full size images) , display them thumbnails on view controller. above how save image:

let filename:string = self.stickerused + ".png" var arraypaths = nssearchpathfordirectoriesindomains(.documentdirectory, .userdomainmask, true)[0] nsstring var pngfilename = arraypaths.stringbyappendingpathcomponent(filename) uiimagepngrepresentation(screenshot).writetofile(pngfilename, atomically:true) nsuserdefaults.standarduserdefaults().setobject(filename, forkey: self.stickerused) nsuserdefaults.standarduserdefaults().synchronize()

following how retrieve images. code first screenshot , setting image in uiimageview (done 12 other uiimageviews):

    var defaultname:string = "sticker1.png"     let path = nssearchpathfordirectoriesindomains(         .documentdirectory, .userdomainmask, true)[0] nsstring     let filename = nsuserdefaults.standarduserdefaults()         .stringforkey("sticker1") ?? defaultname     let imagepath = path.stringbyappendingpathcomponent(filename)     let image = uiimage(contentsoffile: imagepath )     sticker1_view.image = resizeimage(image!, newsize: cgsizemake(overview.frame.width/4, overview.frame.height/4))

this how scale them down after loaded memory: 

      func resizeimage(image: uiimage, newsize: cgsize) -> (uiimage) {     let newrect = cgrectintegral(cgrectmake(0,0, newsize.width, newsize.height))     let imageref = image.cgimage      uigraphicsbeginimagecontextwithoptions(newsize, false, 0)     let context = uigraphicsgetcurrentcontext()      // set quality level use when rescaling     cgcontextsetinterpolationquality(context, kcginterpolationhigh)     let flipvertical = cgaffinetransformmake(1, 0, 0, -1, 0, newsize.height)      cgcontextconcatctm(context, flipvertical)     // draw context; scales image     cgcontextdrawimage(context, newrect, imageref)      let newimageref = cgbitmapcontextcreateimage(context) cgimage     let newimage = uiimage(cgimage: newimageref)      // resized image context , uiimage     uigraphicsendimagecontext()      return newimage! }

the app works fine first time. switch between 2 view controllers gets slow , memory warning leads crash. understand researching images getting cached. need clear cache or not multiple load images. or maybe in didreceivememorywarning() in order stop crashing. should ?

you can use profile(product->profile) see, if there memory leak in program.

you can tutorial

hope can address memory issue.


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