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General

Weird iPad errors: Unknown -35, required disk not found

Had moments of worry this morning trying to sync and install an app on the iPad. iTunes first reported an unknown error -35, then told me that ‘the required disk was not found’.

How to solve “required disk cannot be found”:
He had me do the following:
1. go to home folder in finder
2. open pictures folder
3. right click on iphoto library and click on show package contents
4. Find “ipod photo cache” file and drag to desktop
5. Close finder
6. Reopen itunes and sync ipad
7. The ipod photo cache rebuilds itself
Source: http://goo.gl/7p5p5

Unknown error -35 was solved by plugging in the iPad cable to the actual computer. It was originally connected to the corded Apple keyboard. Apparently not enough juice flowing through the keyboard to support the iPad.

Lessons learned.

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Computing General ios iphone

SQLite ORDER BY does not work on integers: time for an index

My current project uses SQLite as it is really the only game in town on iOS. SQLite indexes provide an incredible performance boosts when you are dealing with large datasets. They apparently play a crucial role when it comes to something of a foregone conclusion in other databases – sorting.

What stumped my colleagues and I was that we had a database table where one of the columns had an INT (and also tested using an INTEGER) type (and yes – they are all NUMERIC to SQLite) – and ORDER BY kept returning incorrectly sorted results. According to this post on Stack Overflow, when you have a SQLite query that uses the ORDER BY, it may rely on temporary tables. Those in turn 'confuse' the database when it runs the query to sort your table.

The answer – add an index. Something as simple as

CREATE INDEX index_name ON table_name
(
   NAME_OF_COLUMN_TO_SORT ASC
);

Once you add it – you are, well – sorted out.

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Computing ios iphone

Positioning UIPopoverController

The iPad has a great UI control – the UIPopoverController – most notably used in its email app when it is in portrait mode. To show, or 'present' a UIPopoverController you have two methods:

– presentPopoverFromBarButtonItem:permittedArrowDirections:animated: 
which is used to present the popover from a UIBarButton in, say, a navigation bar.

– presentPopoverFromRect:inView:permittedArrowDirections:animated:
which is used to present the popover from a location specified by a CGRect as its first parameter.

Unlike other UI controls, this CGRect actually specifies the location of the UIControl you want the popover to point at, or at least be next to. For example, the button that triggers the showing of the UIPopoverController. That is, the UIPopoverController does not use that CGRect for its own positioning – but as an 'advice' where it should be hovering.

You can also tell it where you want it to hover using the permittedArrowDirections flags, which will try to place it say, above (if the arrow direction flag is down), to the left (if the arrow direction is right), etc.

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