{"id":28839,"date":"2020-05-04T13:43:40","date_gmt":"2020-05-04T17:43:40","guid":{"rendered":"https:\/\/mjtsai.com\/blog\/?p=28839"},"modified":"2020-05-19T15:51:30","modified_gmt":"2020-05-19T19:51:30","slug":"nsprogress-documentation-conflicts","status":"publish","type":"post","link":"https:\/\/mjtsai.com\/blog\/2020\/05\/04\/nsprogress-documentation-conflicts\/","title":{"rendered":"NSProgress Documentation Conflicts"},"content":{"rendered":"

Curtis Herbert<\/a>:<\/p>\n

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Wait...what? The new NSProgress<\/code> stuff on NSOperationQueue<\/code> says you have to call super.start()<\/code> to contribute towards progress, but Foundation docs for NSOperation<\/code> say to never call super.start()<\/code> O.o<\/p>\n<\/blockquote>\n\n

NSOperation.h:<\/p>\n

The progress<\/code> property represents a total progress of the operations executed in the queue. By default NSOperationQueue does not report progress until the totalUnitCount<\/code> of the progress is set. When the totalUnitCount<\/code> property of the progress is set the queue then opts into participating in progress reporting. When enabled, each operation will contribute 1 unit of completion to the overall progress of the queue for operations that are finished by the end of main (operations that override start<\/code> and do not invoke super<\/code> will not contribute to progress).<\/p><\/blockquote>\n\n

NSOperation documentation<\/a>:<\/p>\n

At no time in your start<\/code> method should you ever call super<\/code>. When you define a concurrent operation, you take it upon yourself to provide the same behavior that the default start<\/code> method provides, which includes starting the task and generating the appropriate KVO notifications.<\/p><\/blockquote>\n\n

Matej Bukovinski<\/a>:<\/p>\n

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Let’s just replace a NSProgress<\/code> helper with built-in API. Easy. A day later we’re still trying to figure out if we even know how this API is supposed to be used. Spoiler:<\/em> The header is right. As usual. Never rely just on the generated docs.<\/p>\n<\/blockquote>\n\n

NSProgress.h:<\/p>\n

-isIndeterminate<\/code> returns YES<\/code> when the value of the totalUnitCount<\/code> or completedUnitCount<\/code> property is less than zero. Zero values for both of those properties indicates that there turned out to not be any work to do after all; -isIndeterminate<\/code> returns NO<\/code> and -fractionCompleted<\/code> returns 1.0 in that case.<\/p><\/blockquote>\n\n

NSProgress documentation<\/a>:<\/p>\n

Progress is indeterminate when the value of both totalUnitCount<\/code> and completedUnitCount<\/code> are zero.<\/p><\/blockquote>\n\n

Previously:<\/p>\n