NSStringToUIColor with alpha

+(UIColor*)toUIColor:(NSString*)hexColorString {

unsigned int c;

if ([hexColorString characterAtIndex:0] == '#') {

[[NSScanner scannerWithString:[hexColorString substringFromIndex:1]] scanHexInt:&c];

} else {

[[NSScanner scannerWithString:hexColorString] scanHexInt:&c];

}

if([hexColorString length] > 7) {

return [UIColor colorWithRed:((c & 0xff000000) >> 24)/255.0 green:((c & 0xff0000) >> 16)/255.0 blue:((c & 0xff00) >> 8)/255.0 alpha:(c & 0xff)/255.0];

}

return [UIColor colorWithRed:((c & 0xff0000) >> 16)/255.0 green:((c & 0xff00) >> 8)/255.0 blue:(c & 0xff)/255.0 alpha:1.0];

}

[Color toUIColor:#001122];
[Color toUIColor:#001122aa];

Elapsed time

NSDate *startTime = [NSDate date];

...

NSLog(@"Elapsed time: %f", -[startTime timeIntervalSinceNow]);

Recursively removing XCode build directories before SVN import, commit, or add

In Terminal, cd to the repository directory to be checked into SVN

rm -rf `find . -type d -name build`


This will remove all the build directories in all the sub directories e.g. when trunk contains multiple projects.

Checking iOS version at runtime

@interface DeviceUtil : NSObject {

}

+(BOOL)osVersionSupported:(NSString*)version;

@end

#import "DeviceUtil.h"

@implementation DeviceUtil

//    e.g. [DeviceUtil osVersionSupported:@"4.1"]

+(BOOL)osVersionSupported:(NSString*)version {

    NSString *currSysVer = [[UIDevice currentDevice] systemVersion];

    BOOL osVersionSupported = ([currSysVer

            compare:version

            options:NSNumericSearch] != NSOrderedAscending);

    return osVersionSupported;

}

@end

#warning #error

#warning
The directive #warning is similar to #error, however the preprocessor doesn’t stop when it finds this directive, it simply displays the message to the console and keeps on with the task at hand. One common use of #warning is to display information regarding deprecated code:

#warning : This method is deprecated, use someNewMethod instead

#error
When the preprocessor runs into the #error directive, it will write an error to the console and generate a compile time error. You can also include a text string which is displayed as an error message.

#error : Change this value to your Flickr key
NSString* const FlickrAPIKey = @"your-key-here";


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