UIColor值和颜色的十六进制值（hex值）的互相转换

+ (UIColor*) colorWithHex:(NSInteger)hexValue alpha:(CGFloat)alphaValue
{
return [UIColor colorWithRed:((float)((hexValue & 0xFF0000) >> 16))/255.0
green:((float)((hexValue & 0xFF00) >> 8))/255.0
blue:((float)(hexValue & 0xFF))/255.0 alpha:alphaValue];
}

+ (UIColor*) colorWithHex:(NSInteger)hexValue
{
return [UIColor colorWithHex:hexValue alpha:1.0];
}

+ (NSString *) hexFromUIColor: (UIColor*) color {
if (CGColorGetNumberOfComponents(color.CGColor) < 4) {
const CGFloat *components = CGColorGetComponents(color.CGColor);
color = [UIColor colorWithRed:components[0]
green:components[0]
blue:components[0]
alpha:components[1]];
}

if (CGColorSpaceGetModel(CGColorGetColorSpace(color.CGColor)) != kCGColorSpaceModelRGB) {
return [NSString stringWithFormat:@"#FFFFFF"];
}

return [NSString stringWithFormat:@"#XXX", (int)((CGColorGetComponents(color.CGColor))[0]*255.0),
(int)((CGColorGetComponents(color.CGColor))[1]*255.0),
(int)((CGColorGetComponents(color.CGColor))[2]*255.0)];
}