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Editorial Team
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Asked: 2026-06-09T20:06:56+00:00

I have class MyOperation : NSOperation with @property (nonatomic, retain) NSString *oID; And sometimes

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I have class MyOperation : NSOperation with @property (nonatomic, retain) NSString *oID;

And sometimes I need to cancel operation with specific oID. I’m trying to do this:

NSArray *operations = operationQueue.operations;
NSPredicate *predicate = [NSPredicate predicateWithFormat:[NSString stringWithFormat: @"oID == %@", _specificID]];
NSArray *arrayOperations = [operations filteredArrayUsingPredicate: predicate];

and get error:

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unable to parse the format string "oID == 0f5db97b-f127-4425-ad79-451d1f204016"'

Is it possible to filter operation from NSOperationQueue?

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1 Answer

  1. Editorial Team

    Your problem is that you are formatting a string, then sending that to the Predicate constructor method. It’s already a formatter, and knows how to format the data you give it.

    Basically, you need the format to look like:

    oID == "0f5db97b-f127-4425-ad79-451d1f204016"

    but you are getting

    oID == 0f5db97b-f127-4425-ad79-451d1f204016

    If you use the formatter by itself, you should get past this issue…

    NSPredicate *predicate = [NSPredicate predicateWithFormat: @"oID == %@", _specificID];

    NOTE: The predicate formatter knows it should handle strings specially, and automatically adds the extra quotation characters when you pass a string to be formatted by %@‘

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