[[UISearchBar appearance] setSearchFieldBackgroundImage:[self __searchFieldBackgroundImage] forState:UIControlStateNormal];

UITextField*textField = [UITextField appearanceWhenContainedInInstancesOfClasses:@[[UISearchBar class],[UINavigationBar class]]];

[textField setDefaultTextAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:13]}];

- (UIImage*)__searchFieldBackgroundImage {

UIColor*color = BXS_F2_F2_F2_COLOR;

CGFloatcornerRadius = 3;

CGRectrect =CGRectMake(0,0,28,28);

UIBezierPath*roundedRect = [UIBezierPath bezierPathWithRoundedRect:rect cornerRadius:cornerRadius];

roundedRect.lineWidth=0;

UIGraphicsBeginImageContextWithOptions(rect.size,NO,0.0f);

[color setFill];

[roundedRect fill];

[roundedRect stroke];

[roundedRect addClip];

UIImage *image =UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return image;

}

這里設置了背景的顏色和字體，與之前的樣式一致；

解決了UISearchBar添加在UINavigationBar 上面的時候，pushVC，然后pop之后字體變大的問題。