Delaying A Label Updated From Within connection:didReceiveData:data

Question

I'm working on a download manager and I'm trying to update labels indicating the download speed and the percentage left.

It updates way too fast within connection:didReceiveData though, and using a performSelector and delaying it from that method doesn't work (it just delays it for that long before starting).

What should I do to update something like download speed or percentage left?

score 1 · Answer 1 · answered Apr 18 '12 at 11:27

1

It would be helpful to see how you calculate speed and percentage but one approach will be :

Calculate time elapsed (in seconds) between two calls of connection:didReceiveData
Take the size of the current received data (let's call it size)
Sum total data size downloaded so far (lets call it downloadedSize)
Speed = size / timeElapsed
Percentage = downloadedSize / Total data size (Assuming you have it)
Convert to desired units
Update the labels (I do not see why you should delay here)

answered Apr 18 '12 at 11:27

giorashc

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I think he wants to delay it to prevent the label from updating every frame, or at least so fast that the user can't read it... – Christian Schnorr Apr 18 '12 at 11:39
Yeah, I just want to prevent the label from updating every frame. – aroooo Apr 18 '12 at 11:50
Do you truncate your calculations ? (e.g display only 1.3 for 1.333333 etc ...) – giorashc Apr 18 '12 at 11:57
Yeah, my calculations are truncated. – aroooo Apr 19 '12 at 07:49

score 1 · Accepted Answer · answered Apr 18 '12 at 11:35

1

If you don't want to update the display as quickly as possible, just keep note of the time when you last updated it. If the current time is not at least, say, 0.5 seconds since the last update, just don't update on this pass.

answered Apr 18 '12 at 11:35

Ken Thomases

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Delaying A Label Updated From Within connection:didReceiveData:data

2 Answers2