OC代码片段

//打印指针的内存地址

    NSLog(@"%x",self.redView);

    //打印指针指向对象的内存地址

    NSLog(@"%p",self.redView);

    //打印对象

    NSLog(@"%@",self.redView);

//从数组中取值，要注意数组越界
    if (leftLanguageIndex + 1 > availableVoices.count) {
        leftLanguageIndex = availableVoices.count - 1;
    }
    if (rightLanguageIndex + 1 > availableVoices.count) {
        rightLanguageIndex = availableVoices.count - 1;
    }

//代理协议要遵守<NSObject>
@protocol secViewControllerDelegate <NSObject>
//实现代理协议要先判断delegate是否能够相应对应的方法！！
//不判断会崩溃！！！
 if ([self.delegate respondsToSelector:@selector(returnString:)]) {
        [self.delegate returnString:@"dfs"];
    }

    //监听通知中心，由于APPDelegate只会调用一次，所以写在这里最好
    [self setUpNotification];

//通过动画CAKeyFrameAnimation来写闪烁效果
 CAKeyframeAnimation *animation = [CAKeyframeAnimation animationWithKeyPath:@"opacity"];
    animation.values=@[@1,@0,@1];
    animation.repeatCount=MAXFLOAT;
    animation.duration = 2;
    animation.removedOnCompletion = NO;
    [button.layer addAnimation:animation forKey:nil];

 //隐藏导航栏分割线
        [[UINavigationBar appearance] setShadowImage:[UIImage new]];
        //设置导航栏背景颜色
        [UINavigationBar appearance].barTintColor=kNavBackColor;
        //设置导航栏标题 大小 颜色
        NSDictionary * navigationTitleAttDic = @{NSFontAttributeName:[UIFont systemFontOfSize:18],NSForegroundColorAttributeName:UIColorFromRGB(74,74,74)};
        [[UINavigationBar appearance] setTitleTextAttributes:navigationTitleAttDic];

 @try{
        NSArray *array = [NSArray new];
        NSLog(@"%@",array[0]);
    }
    @catch(NSException *exception){
        NSLog(@"%@",exception);
    }
    @finally{
        
    }

子类重写基类的方法，要先调用下父类的方法