将NavigationBar设置透明

将NavigationBar设置透明（仅将指定视图控制器进行透明处理），步骤如下：
1.在视图控制器的头文件中实现UINavigationControllerDe<wbr>legate</wbr>，
例如：@interface PicturePreviewViewContro<wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">ller : UIViewController&lt;</span><span style="word-wrap:normal; word-break:normal; line-height:21px; font-family:simsun; font-size:14px; color:rgb(255,0,0)">UINavigationControllerDe<wbr>legate</wbr></span><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">&gt;</span><br style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">2.在实现类中加入这个代理的方法及具体操作如</span><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">下：</span><br style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="word-wrap:normal; word-break:normal; line-height:21px; font-family:simsun; font-size:14px; color:rgb(255,0,0)">- (void) navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated</span><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">{</span><br style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">// 如果进入的是当前视图控制器</span><br style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">if (viewController == self) {</span><br style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">// 背景设置为黑色</span><br style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">self.navigationController.navigationBar.</span><span style="word-wrap:normal; word-break:normal; line-height:21px; font-family:simsun; font-size:14px; color:rgb(255,0,0)">tintColor</span><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">= [UIColor colorWithRed:0.000 green:0.000 blue:0.000 alpha:1.000];</span><br style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">// 透明度设置为0.3</span><br style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">self.navigationController.navigationBar.</span><span style="word-wrap:normal; word-break:normal; line-height:21px; font-family:simsun; font-size:14px; color:rgb(255,0,0)">alpha</span><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">= 0.300;</span><br style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">// 设置为半透明</span><br style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">self.navigationController.navigationBar.</span><span style="word-wrap:normal; word-break:normal; line-height:21px; font-family:simsun; font-size:14px; color:rgb(255,0,0)">translucent</span><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">=</span><span style="word-wrap:normal; word-break:normal; line-height:21px; font-family:simsun; font-size:14px; color:rgb(255,0,0)">YES</span><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">;</span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><br style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">} else {</span><br style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">// 进入其他视图控制器</span><br style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">self.navigationController.navigationBar.alpha = 1;</span><br style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">// 背景颜色设置为系统默认颜色 </span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><br style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">self.navigationController.navigationBar.tintColor = nil;</span><br style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">self.navigationController.navigationBar.translucent = NO;</span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><br style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px">}</span><br style="color:rgb(70,70,70); font-family:simsun; font-size:14px; line-height:21px"></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>

}