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Hex + CSS extensions to create UIColors from hex colour values or CSS colour strings.
//
// UIColor+Hex.h
//
// Created by Tom Adriaenssen on 13/01/11.
//
@interface UIColor (Hex)
+ (UIColor*) colorWithCSS: (NSString*) css;
+ (UIColor*) colorWithHex: (NSUInteger) hex;
@end
//
// UIColor+Hex
//
// Created by Tom Adriaenssen on 13/01/11.
//
#import "UIColor+Hex.h"
@implementation NSString (LeftPadding)
// taken from http://stackoverflow.com/questions/964322/padding-string-to-left-with-objective-c
- (NSString *) stringByPaddingTheLeftToLength:(NSUInteger) newLength withString:(NSString *) padString startingAtIndex:(NSUInteger) padIndex
{
if ([self length] <= newLength)
return [[@"" stringByPaddingToLength:newLength - [self length] withString:padString startingAtIndex:padIndex] stringByAppendingString:self];
else
return [[self copy] autorelease];
}
@end
@implementation UIColor (Hex)
+ (UIColor*) colorWithCSS: (NSString*)css {
if (css == nil || [css length] == 0)
return [UIColor blackColor];
if ([css characterAtIndex:0] == '#')
css = [css substringFromIndex:1];
NSString *a, *r, *g, *b;
int len = [css length];
if (len == 6) {
six:
a = @"FF";
r = [css substringWithRange:NSMakeRange(0, 2)];
g = [css substringWithRange:NSMakeRange(2, 2)];
b = [css substringWithRange:NSMakeRange(4, 2)];
}
else if (len == 8) {
eight:
a = [css substringWithRange:NSMakeRange(0, 2)];
r = [css substringWithRange:NSMakeRange(2, 2)];
g = [css substringWithRange:NSMakeRange(4, 2)];
b = [css substringWithRange:NSMakeRange(6, 2)];
}
else if (len == 3) {
three:
a = @"FF";
r = [css substringWithRange:NSMakeRange(0, 1)];
r = [r stringByAppendingString:a];
g = [css substringWithRange:NSMakeRange(1, 1)];
g = [g stringByAppendingString:a];
b = [css substringWithRange:NSMakeRange(2, 1)];
b = [b stringByAppendingString:a];
}
else if (len == 4) {
a = [css substringWithRange:NSMakeRange(0, 1)];
a = [a stringByAppendingString:a];
r = [css substringWithRange:NSMakeRange(1, 1)];
r = [r stringByAppendingString:a];
g = [css substringWithRange:NSMakeRange(2, 1)];
g = [g stringByAppendingString:a];
b = [css substringWithRange:NSMakeRange(3, 1)];
b = [b stringByAppendingString:a];
}
else if (len == 5 || len == 7) {
css = [@"0" stringByAppendingString:css];
if (len == 5) goto six;
goto eight;
}
else if (len < 3) {
css = [css stringByPaddingTheLeftToLength:3 withString:@"0" startingAtIndex:0];
goto three;
}
else if (len > 8) {
css = [css substringFromIndex:len-8];
goto eight;
}
else {
css = @"FF000000";
goto eight;
}
// parse each component separetely. This gives more accurate results than
// throwing it all together in one string and use scanf on the global string.
a = [@"0x" stringByAppendingString:a];
r = [@"0x" stringByAppendingString:r];
g = [@"0x" stringByAppendingString:g];
b = [@"0x" stringByAppendingString:b];
uint av, rv, gv, bv;
sscanf([a cStringUsingEncoding:NSASCIIStringEncoding], "%x", &av);
sscanf([r cStringUsingEncoding:NSASCIIStringEncoding], "%x", &rv);
sscanf([g cStringUsingEncoding:NSASCIIStringEncoding], "%x", &gv);
sscanf([b cStringUsingEncoding:NSASCIIStringEncoding], "%x", &bv);
return [UIColor colorWithRed: rv / ((CGFloat)0xFF)
green: gv / ((CGFloat)0xFF)
blue: bv / ((CGFloat)0xFF)
alpha: av / ((CGFloat)0xFF)];
}
+ (UIColor*) colorWithHex: (uint)hex {
CGFloat red, green, blue, alpha;
red = ((CGFloat)((hex >> 16) & 0xFF)) / ((CGFloat)0xFF);
green = ((CGFloat)((hex >> 8) & 0xFF)) / ((CGFloat)0xFF);
blue = ((CGFloat)((hex >> 0) & 0xFF)) / ((CGFloat)0xFF);
alpha = hex > 0xFFFFFF ? ((CGFloat)((hex >> 24) & 0xFF)) / ((CGFloat)0xFF) : 1;
return [UIColor colorWithRed: red green:green blue:blue alpha:alpha];
}
@end

To1ne commented Sep 2, 2015

Thx, but I couldn't help myself to rewrite it a bit:

+ (UIColor *)colorWithHex:(uint32_t)hex {
  CGFloat a = hex <= 0xFFFFFF ? 1.0 :
              ((CGFloat)((hex >> 24) & 0xFF)) / ((CGFloat)0xFF);
  CGFloat r = ((CGFloat)((hex >> 16) & 0xFF)) / ((CGFloat)0xFF);
  CGFloat g = ((CGFloat)((hex >>  8) & 0xFF)) / ((CGFloat)0xFF);
  CGFloat b = ((CGFloat)((hex >>  0) & 0xFF)) / ((CGFloat)0xFF);

  return [UIColor colorWithRed:r green:g blue:b alpha:a];
}
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