1.设置系统默认的背景框，圆角等属性：推荐网址1：http://www.cnblogs.com/-ios/p/5948643.html
推荐网址2：http://www.jianshu.com/p/57ba04b7e389
以下是个人实现原理：
UISearchBar *sbSearchBar =[[UISearchBar alloc]init];
/**设置背景色*/
UIImage* searchBarBg =[self GetImageWithColor:[UIColor clearColor]andHeight:32.0f];
//设置背景图片
[sbSearchBar setBackgroundImage:searchBarBg];
//设置背景色
[sbSearchBar setBackgroundColor:[UIColor clearColor]];
//更改search圆角
UITextField *searchField =[sbSearchBar valueForKey:@"searchField"];
if(searchField){
[searchField setBackgroundColor:[UIColor whiteColor]];
searchField.layer.cornerRadius = 2.0f;
searchField.layer.borderColor =[UIColor sam_colorWithHex:@"d8d8d8"].CGColor;
searchField.layer.borderWidth = 1;
searchField.layer.masksToBounds = YES;
}
sbSearchBar.placeholder = @"请输入关键字";
[self.view addSubview:sbSearchBar];
[sbSearchBar mas_makeConstraints:^(MASConstraintMaker *make){
make.left.mas_equalTo(scanBtn.mas_right);
make.top.bottom.right.mas_equalTo(scanOrSearchV);
}];
-(UIImage*)GetImageWithColor:(UIColor*)color andHeight:(CGFloat)height
{
CGRect r= CGRectMake(0.0f,0.0f,1.0f,height);
UIGraphicsBeginImageContext(r.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context,[color CGColor]);
CGContextFillRect(context,r);
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
