UIColor与⼗六进制字符串互转（整理）UIColor转⼗六进制字符串
⽅法⼀：经过测试发现部分颜⾊会转化为#fffff（五个f），转化残缺导致最后颜⾊⽆法还原，不推荐使⽤。
// UIColor转#ffffff格式的字符串
+ (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]];
}
cstring转为intif (CGColorSpaceGetModel(CGColorGetColorSpace(color.CGColor)) != kCGColorSpaceModelRGB) {
return [NSString stringWithFormat:@"#FFFFFF"];
}
return [NSString stringWithFormat:@"#%x%x%x", (int)((CGColorGetComponents(color.CGColor))[0]*255.0),            (int)((CGColorGetComponents(color.CGColor))[1]*255.0),
(int)((CGColorGetComponents(color.CGColor))[2]*255.0)];
}
⽅法⼆：完美转化为#ffffff格式，暂未发现问题，推荐使⽤。
// UIColor转#ffffff格式的字符串
+ (NSString *)hexStringFromColor:(UIColor *)color {
const CGFloat *components = CGColorGetComponents(color.CGColor);
CGFloat r = components[0];
CGFloat g = components[1];
CGFloat b = components[2];
return [NSString stringWithFormat:@"#%02lX%02lX%02lX",
lroundf(r * 255),
lroundf(g * 255),
lroundf(b * 255)];
}
⼗六进制字符串转UIColor
⽅法⼀：
+ (CGFloat) colorComponentFrom: (NSString *) string start: (NSUInteger) start length: (NSUInteger) length {
NSString *substring = [string substringWithRange: NSMakeRange(start, length)];
NSString *fullHex = length == 2 ? substring : [NSString stringWithFormat: @"%@%@", substring, substring];
unsigned hexComponent;
[[NSScanner scannerWithString: fullHex] scanHexInt: &hexComponent];
return hexComponent / 255.0;
}
+ (UIColor *) colorWithHexString: (NSString *) hexString {
NSString *colorString = [[hexString stringByReplacingOccurrencesOfString: @"#" withString: @""] uppercaseString];
CGFloat alpha, red, blue, green;
switch ([colorString length]) {
case3: // #RGB
alpha = 1.0f;
red  = [self colorComponentFrom: colorString start: 0 length: 1];
green = [self colorComponentFrom: colorString start: 1 length: 1];
blue  = [self colorComponentFrom: colorString start: 2 length: 1];
break;
case4: // #ARGB
alpha = [self colorComponentFrom: colorString start: 0 length: 1];
red  = [self colorComponentFrom: colorString start: 1 length: 1];
green = [self colorComponentFrom: colorString start: 2 length: 1];
blue  = [self colorComponentFrom: colorString start: 3 length: 1];
break;
case6: // #RRGGBB
alpha = 1.0f;
red  = [self colorComponentFrom: colorString start: 0 length: 2];
green = [self colorComponentFrom: colorString start: 2 length: 2];
blue  = [self colorComponentFrom: colorString start: 4 length: 2];
break;
case8: // #AARRGGBB
alpha = [self colorComponentFrom: colorString start: 0 length: 2];
red  = [self colorComponentFrom: colorString start: 2 length: 2];
green = [self colorComponentFrom: colorString start: 4 length: 2];
blue  = [self colorComponentFrom: colorString start: 6 length: 2];
break;
default:
return nil;
}
return [UIColor colorWithRed: red green: green blue: blue alpha: alpha];
}
⽅法⼆：
+ (UIColor *)colorWithHexString:(NSString *)hexString alpha:(CGFloat)alphaValue {
NSString *cString = [[hexString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString]; if (cString.length < 6)
return [UIColor clearColor];
if ([cString hasPrefix:@"0X"])
cString = [cString substringFromIndex:2];
if ([cString hasPrefix:@"#"])
cString = [cString substringFromIndex:1];
if (cString.length != 6)
return [UIColor clearColor];
NSRange range;
range.location = 0;
range.length = 2;
NSString *rString = [cString substringWithRange:range];
range.location = 2;
NSString *gString = [cString substringWithRange:range];
range.location = 4;
NSString *bString = [cString substringWithRange:range];
unsigned int r, g, b;
[[NSScanner scannerWithString:rString] scanHexInt:&r];
[[NSScanner scannerWithString:gString] scanHexInt:&g];
[[NSScanner scannerWithString:bString] scanHexInt:&b];
// 注意：myColor是⾃定义宏
//#define myColor(R, G, B, A) [UIColor colorWithRed:R/255.0 green:G/255.0 blue:B/255.0 alpha:A]
return myColor(r, g, b, alphaValue);
}

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