How to check if QLPreview is loaded?











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I have QLPreviewView and I need to check if the preview is loaded in n seconds after assigning QLPreviewItem. QLPreviewView and QLPreviewItem don't have any events for loading and any fields to check it, so I came with checking view hierarchy. It works pretty good with my few test cases, but ofc hierarchy can be changed in new versions of mac OS. Another solution could be working with field displayState. It's always nil when preview isn't loaded, but it can be nil when preview is loaded (for example for folder preview which doesn't have state). So even if we have displayState equal to nil, we still need to check if file can own any preview state at all, i.e. this solution depends on concrete mac OS version too.



Is there any tricks which are better then observing view hierarchy? Or may be is there any alternatives to QLPreviews?






macos cocoa appkit quicklook qlpreviewcontroller







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    down vote

    favorite












    I have QLPreviewView and I need to check if the preview is loaded in n seconds after assigning QLPreviewItem. QLPreviewView and QLPreviewItem don't have any events for loading and any fields to check it, so I came with checking view hierarchy. It works pretty good with my few test cases, but ofc hierarchy can be changed in new versions of mac OS. Another solution could be working with field displayState. It's always nil when preview isn't loaded, but it can be nil when preview is loaded (for example for folder preview which doesn't have state). So even if we have displayState equal to nil, we still need to check if file can own any preview state at all, i.e. this solution depends on concrete mac OS version too.



    Is there any tricks which are better then observing view hierarchy? Or may be is there any alternatives to QLPreviews?






    macos cocoa appkit quicklook qlpreviewcontroller







    share|improve this question
























      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      I have QLPreviewView and I need to check if the preview is loaded in n seconds after assigning QLPreviewItem. QLPreviewView and QLPreviewItem don't have any events for loading and any fields to check it, so I came with checking view hierarchy. It works pretty good with my few test cases, but ofc hierarchy can be changed in new versions of mac OS. Another solution could be working with field displayState. It's always nil when preview isn't loaded, but it can be nil when preview is loaded (for example for folder preview which doesn't have state). So even if we have displayState equal to nil, we still need to check if file can own any preview state at all, i.e. this solution depends on concrete mac OS version too.



      Is there any tricks which are better then observing view hierarchy? Or may be is there any alternatives to QLPreviews?






      macos cocoa appkit quicklook qlpreviewcontroller







      share|improve this question













      I have QLPreviewView and I need to check if the preview is loaded in n seconds after assigning QLPreviewItem. QLPreviewView and QLPreviewItem don't have any events for loading and any fields to check it, so I came with checking view hierarchy. It works pretty good with my few test cases, but ofc hierarchy can be changed in new versions of mac OS. Another solution could be working with field displayState. It's always nil when preview isn't loaded, but it can be nil when preview is loaded (for example for folder preview which doesn't have state). So even if we have displayState equal to nil, we still need to check if file can own any preview state at all, i.e. this solution depends on concrete mac OS version too.



      Is there any tricks which are better then observing view hierarchy? Or may be is there any alternatives to QLPreviews?






      macos cocoa appkit quicklook qlpreviewcontroller




      macos cocoa appkit quicklook qlpreviewcontroller






      share|improve this question













      share|improve this question











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      share|improve this question










      asked Nov 8 at 13:49









      Nikolai Galiullin

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