颜色设置

1、不想每次都除255.0

+ (UIColor *)colorWithR:(CGFloat)red G:(CGFloat)green B:(CGFloat)blue {

return [UIColor colorWithRed:red/255.0 green:green/255.0 blue:blue/255.0 alpha:1];

}

2、随机色

+ (UIColor *)randomColor{

return [UIColor colorWithRed:arc4random()%256/255.0 green:arc4random()%256/255.0 blue:arc4random()%256/255.0 alpha:1];

}

3、以16进制设置色值，如：#FF6752 (以下分是否需要设置alpha)

（1）不需要设置alpha

+ (UIColor*)colorWithHexString:(NSString*)colorStr {

NSString *cString = [[colorStr stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString];

if ([cString hasPrefix:@"#"]) cString = [cString substringFromIndex:1];

if ([cString length] != 6) return [UIColor blackColor];

// Separate into r, g, b substrings

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];

// Scan values

unsigned int r, g, b;

[[NSScanner scannerWithString:rString] scanHexInt:&r];

[[NSScanner scannerWithString:gString] scanHexInt:&g];

[[NSScanner scannerWithString:bString] scanHexInt:&b];

return [UIColor colorWithRed:((float) r / 255.0f)

green:((float) g / 255.0f)

blue:((float) b / 255.0f)

alpha:1.0f];

}

（2）需要设置alpha

+ (UIColor*)colorWithHexString:(NSString*)colorStr alpha:(CGFloat)alpha {

NSString *cString = [[colorStr stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString];

if ([cString hasPrefix:@"#"]) cString = [cString substringFromIndex:1];

if ([cString length] != 6) return [UIColor blackColor];

// Separate into r, g, b substrings

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];

// Scan values

unsigned int r, g, b;

[[NSScanner scannerWithString:rString] scanHexInt:&r];

[[NSScanner scannerWithString:gString] scanHexInt:&g];

[[NSScanner scannerWithString:bString] scanHexInt:&b];

return [UIColor colorWithRed:((float) r / 255.0f)

green:((float) g / 255.0f)

blue:((float) b / 255.0f)

alpha:alpha];

}