自定义UISearchBar外观

1. 设置背景色

我以白色的背景色为例，下面看看代码：

//1. 设置背景颜色
    //设置背景图是为了去掉上下黑线
    self.customSearchBar.backgroundImage = [[UIImage alloc] init];
    // 设置SearchBar的颜色主题为白色
    self.customSearchBar.barTintColor = [UIColor whiteColor];

2. 设置边框颜色和圆角

//2. 设置圆角和边框颜色
    UITextField *searchField = [self.customSearchBar valueForKey:@"searchField"];
    if (searchField) {
        [searchField setBackgroundColor:[UIColor whiteColor]];
        searchField.layer.cornerRadius = 14.0f;
        searchField.layer.borderColor = [UIColor colorWithRed:247/255.0 green:75/255.0 blue:31/255.0 alpha:1].CGColor;
        searchField.layer.borderWidth = 1;
        searchField.layer.masksToBounds = YES;
    }

这段代码有个特别的地方就是通过KVC获得到UISearchBar的私有变量

searchField（类型为UITextField），设置SearchBar的边框颜色和圆角实际上也就变成了设置searchField的边框颜色和圆角，你可以试试直接设置SearchBar.layer.borderColor和cornerRadius，会发现这样做是有问题的。 

3. 设置按钮（取消按钮）的文字和文字颜色

//3. 设置按钮文字和颜色
    [self.customSearchBar fm_setCancelButtonTitle:@"取消"];
    self.customSearchBar.tintColor = [UIColor colorWithRed:86/255.0 green:179/255.0 blue:11/255.0 alpha:1];
    //修正光标颜色
    [searchField setTintColor:[UIColor blackColor]];

//其中fm_setCancelButtonTitle是我写的UISearchBar一个分类的方法
- (void)fm_setCancelButtonTitle:(NSString *)title {
    if (IS_IOS9) {
        [[UIBarButtonItem appearanceWhenContainedInInstancesOfClasses:@[[UISearchBar class]]] setTitle:title];
    }else {
        [[UIBarButtonItem appearanceWhenContainedIn:[UISearchBar class], nil] setTitle:title];
    }
}

4. 设置输入框的文字颜色和字体

//4. 设置输入框文字颜色和字体
    [self.customSearchBar fm_setTextColor:[UIColor blackColor]];
    [self.customSearchBar fm_setTextFont:[UIFont systemFontOfSize:14]];

//下面两个方法是UISearchBar分类代码
- (void)fm_setTextColor:(UIColor *)textColor {
    if (IS_IOS9) {
        [UITextField appearanceWhenContainedInInstancesOfClasses:@[[UISearchBar class]]].textColor = textColor;
    }else {
        [[UITextField appearanceWhenContainedIn:[UISearchBar class], nil] setTextColor:textColor];
    }
}

- (void)fm_setCancelButtonTitle:(NSString *)title {
    if (IS_IOS9) {
        [[UIBarButtonItem appearanceWhenContainedInInstancesOfClasses:@[[UISearchBar class]]] setTitle:title];
    }else {
        [[UIBarButtonItem appearanceWhenContainedIn:[UISearchBar class], nil] setTitle:title];
    }
}