I think is fine but If I were you I probably will try to find some kind of
function that gives me the same result as using enumerators
For example in this case I will use UIColor colorWithRed:green:blue:alpha
method and use the radius to determine components of a color
When numerator objects are just a few like this case is ok, but when you have
many many possibilities finding a function is the best option you have.
(although there is no such a function sometimes)
I hope this helps.
Ignacio
Message: 5
Date: Mon, 17 May 2010 14:32:18 +0100
From: Carlton Gibson <li...@noumenal.co.uk>
Subject: Style Advice for using NSEnumerator
To: Cocoa Developer <cocoa-dev@lists.apple.com>
Message-ID: <4509929f-8b9b-4db3-9832-9ad968124...@noumenal.co.uk>
Content-Type: text/plain; charset=us-ascii
Hi All,
I'm still coming to grips with Cocoa and I'm wondering if any list members
would be kind enough just to review a small code fragment for style advice...
The following occurs as part of the drawRect method of a UIView subclass. The
method simply draws concentric circles inside the view. (It's part of an
exercise from the Big Nerd Ranches iPhone Programming book, which I'm enjoying
a lot.)
Originally the routine simply drew the circles in a single color but the book
sets the problem of having it draw them in assorted colors so I came up with
this:
// Set up the stroke colors (and the variables for enumeration)
NSArray *strokeColors = [NSArray arrayWithObjects:
@"redColor", @"orangeColor", @"yellowColor", @"greenColor",
@"blueColor", @"cyanColor", @"magentaColor", nil];
NSEnumerator *enumerator = nil;
NSString *colorString;
// Draw concentric circles from the outside in
for (float currentRadius = maxRadius;
currentRadius > 0;
currentRadius -= 20)
{
// Determine stroke color
if (!(colorString = [enumerator nextObject])) {
enumerator = [strokeColors objectEnumerator];
colorString = [enumerator nextObject];
}
SEL selector = NSSelectorFromString(colorString);
[[UIColor performSelector:selector] setStroke];
// Do Drawing
CGContextAddArc(context, center.x, center.y,
currentRadius, 0.0, M_PI * 2.0, YES);
CGContextStrokePath(context);
}
My question concerns the use the NSEnumerator here. The code works, but is it
_right_? In particular, I'm slightly nervous about relying on the enumerator
being nil first time through the loop, and on testing the return value of
nextObject in the conditional -- perhaps though this is just an idiom I need to
get used to?
Any thoughts from more seasoned Cocoa hands as to how to handle this sort of
situation would be appreciated! :-)
Thanks in advance.
Regards,
Carlton
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