ios - How to get requested image size for iOS8 PhotoKit? -

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i using code below fetching image:

[[phimagemanager defaultmanager] requestimageforasset:asset  targetsize:cgsizemake(800, 600)  contentmode:phimagecontentmodeaspectfill  options:options  resulthandler:^(uiimage *result, nsdictionary *info) {     nslog(@"size:%@",nsstringfromcgsize(result.size));                 }];

i'm requesting image size of 800 x 600, i'm getting image size of 45 x 60, poor-quality.

how can requested image size using photokit?

your (unnati's) self answer work, misses out on number of optimisations apple give in framework images display more quickly.

your original code pretty correct, include options object don't need, , may have been causing problems if had set resizemode incorrectly on it. here code should work you, i've removed options object.

[[phimagemanager defaultmanager]  requestimageforasset:(phasset *)asset  targetsize:cgsizemake(800, 600)  contentmode:phimagecontentmodeaspectfit  options:nil  resulthandler:^(uiimage *result, nsdictionary *info) {      nslog(@"image size:%@",nsstringfromcgsize(result.size));  }];

this should simpler, , give optimisations apple provide framework free. here's explanation of get:

responding low quality image

the framework call result handler multiple times increasing quality images, allowing display user while wait final image. the documentation:

photos may call result handler block more once. photos first calls block provide low-quality image suitable displaying temporarily while prepares high-quality image. (if low-quality image data available, first call may occur before method returns.) when high-quality image ready, photos calls result handler again provide it.

this means resulthandler block needs safe call more once - block in code logs size, , test image 2 log messages, first 1 low quality 40x26 px image, , again high quality image. if open ios photos app, can see low quality images briefly before appear sharpen - what's happening here.

using options.deliverymode = phimagerequestoptionsdeliverymodehighqualityformat prevents behaviour, , resulthandler called once final image, suggest not setting option unless can't devise handler block (in real code) can called multiple times.

returning cached high quality image quickly

to provide final image quickly, framework provide image close requested size in final call resulthandler block, if has 1 cached already. if you're using uiimageview set contentmode of aspect fill or fit, won't problem, specify matching contentmode in image request. example, against test image, second call resulthandler 1280x850 image, larger requested right ballpark. however, setting options.resizemode = phimagerequestoptionsresizemodeexact prevent behaviour , force framework resize fresh copy of image rather using cached copy, takes time.

since photos framework doesn't crop images (even if ask to, that's bug ;-)), won't exact size request, using phimagerequestoptionsresizemodeexact option. example, if request 800x600 image not in 4:3 ratio, photos can't return image of size, gets close can - on latest image, request gets image of 800x531. means need able handle images aren't exact size request, might take advantage of optimisations in framework , avoid using phimagerequestoptionsresizemodeexact. the documentation again:

resizing match target size less efficient using fast resizing option.

(did have set phimagerequestoptionsresizemodefast in original options object, not included in question? may have been causing issue.)

image versions

it's possible request different versions of image, in self answer options.version = phimagerequestoptionsversioncurrent. 1 not required however, default current version.


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