之前网上提供的方法试了很多种 都不能很好的去掉背景色 ，修改背景色方法如下：
searchbar.barStyle = UIBarStyleBlackTranslucent;
searchbar.autocorrectionType = UITextAutocorrectionTypeNo;
searchbar.autocapitalizationType = UITextAutocapitalizationTypeNone;
searchbar.keyboardType = UIKeyboardTypeDefault;
searchbar.backgroundImage = [self SearchImageWithColor:[UIColor clearColor] size:searchbar.bounds.size];定义一个函数 //取消searchbar背景色- (UIImage *)SearchImageWithColor:(UIColor *)color size:(CGSize)size{ CGRect rect = CGRectMake(0, 0, size.width, size.height); UIGraphicsBeginImageContext(rect.size); CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSetFillColorWithColor(context, [color CGColor]); CGContextFillRect(context, rect); UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return image;}原文：http://www.cnblogs.com/seer/p/5162509.html