16进制颜色字符串转为UIColor

把十六进制的颜色转换成十六进制的UIColor颜色

新建UIColor的分类，添加类方法；
在需要用到的地方导入头文件就可；

使用方法：self.view.backgroundColor=[UIColor colorWithRGB:@"#81c52b"];

 +(UIColor*)colorWithhexString:(NSString *)hexString
 {
 NSString *cString = [[hexString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]uppercaseString];//字符串处理
 
 
//例子，stringToConvert #ffffff

if ([cString length] <6)
    
    return [UIColor whiteColor];//如果非十六进制，返回白色

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

if ([cString length] !=6)//去头非十六进制，返回白色
    
    return [UIColor whiteColor];

//分别取RGB的值

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把扫描出的制定的字符串转换成Int类型

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

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

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

//转换为UIColor

return [UIColor colorWithRed:((float) r /255.0f)
                       green:((float) g /255.0f)
                       blue:((float) b /255.0f)
                       alpha:1.0f];
 
 
}