1-->TableView不显示没内容的Cell怎么办?    很简单    self.tableView.tableFooterView = [[UIView alloc] init];    试过的都说好.2-->自定义了leftBarbuttonItem左滑返回手势失效了怎么办?    self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]                                         initWithImage:img                                         style:UIBarButtonItemStylePlain                                         target:self                                         action:@selector(onBack:)];   self.navigationController.interactivePopGestureRecognizer.delegate = (id)self;3-->ScrollView莫名其妙不能在viewController划到顶怎么办?    self.automaticallyAdjustsScrollViewInsets = NO;4-->键盘事件写的好烦躁,都想摔键盘了,怎么办?   1.买个结实的键盘.   2.使用IQKeyboardManager(github上可搜索),用完之后腰也不疼了,腿也不酸了.5-->为什么我的app老是不流畅,到底哪里出了问题?   这个神器叫做:KMCGeigerCounter,快去github搬运吧.6-->怎么在不新建一个Cell的情况下调整（隐藏）separaLine的位置?   _myTableView.separatorInset = UIEdgeInsetsMake(0, screenWidth, 0, 0);(注意: titleLabel的位置也会跟着改变)7-->怎么点击self.view就让键盘收起,需要添加一个tapGestures么 ? NO  - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event  {   [self.view endEditing:YES];  }8-->怎么给每个ViewController设定默认的背景图片?   使用基类啊,少年。9-->想在代码里改在xib里添加的layoutAttributes,但是怎么用代码找啊?    像拉button一样的拉你的约束.nslayoutattribute也是可以拉线的.10-->怎么像safari一样滑动的时候隐藏navigationbar?    navigationController.hidesBarsOnSwipe = Yes11-->导航条返回键带的title太讨厌了,怎么让它消失!     [[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60)                                                     forBarMetrics:UIBarMetricsDefault];                                                     12-->CoreData用起来好烦,语法又臭又长,怎么办?     MagicRecord13-->CollectionView 怎么实现tableview那种悬停的header?     CSStickyHeaderFlowLayout14-->能不能只用一个pan手势来代替UISwipegesture的各个方向?- (void)pan:(UIPanGestureRecognizer *)sender{typedef NS_ENUM(NSUInteger, UIPanGestureRecognizerDirection) {    UIPanGestureRecognizerDirectionUndefined,    UIPanGestureRecognizerDirectionUp,    UIPanGestureRecognizerDirectionDown,    UIPanGestureRecognizerDirectionLeft,    UIPanGestureRecognizerDirectionRight};static UIPanGestureRecognizerDirection direction = UIPanGestureRecognizerDirectionUndefined;switch (sender.state) {    case UIGestureRecognizerStateBegan: {        if (direction == UIPanGestureRecognizerDirectionUndefined) {            CGPoint velocity = [sender velocityInView:recognizer.view];            BOOL isVerticalGesture = fabs(velocity.y) > fabs(velocity.x);            if (isVerticalGesture) {                if (velocity.y > 0) {                    direction = UIPanGestureRecognizerDirectionDown;                } else {                    direction = UIPanGestureRecognizerDirectionUp;                }            }            else {                if (velocity.x > 0) {                    direction = UIPanGestureRecognizerDirectionRight;                } else {                    direction = UIPanGestureRecognizerDirectionLeft;                }            }        }        break;    }    case UIGestureRecognizerStateChanged: {        switch (direction) {            case UIPanGestureRecognizerDirectionUp: {                [self handleUpwardsGesture:sender];                break;            }            case UIPanGestureRecognizerDirectionDown: {                [self handleDownwardsGesture:sender];                break;            }            case UIPanGestureRecognizerDirectionLeft: {                [self handleLeftGesture:sender];                break;            }            case UIPanGestureRecognizerDirectionRight: {                [self handleRightGesture:sender];                break;            }            default: {                break;            }        }        break;    }        case UIGestureRecognizerStateEnded: {        direction = UIPanGestureRecognizerDirectionUndefined;           break;    }    default:        break;}}15-->拉伸图片的时候怎么才能让图片不变形？    1.UIImage *image = [[UIImage imageNamed:@"xxx"] stretchableImageWithLeftCapWidth:10 topCapHeight:10];    2.使用九切片技术16-->怎么播放GIF的时候这么卡，有没有好点的库？     FlipBoard出品的太适合你了： 17-->怎么一句话添加上拉刷新？     使用MJRefresh 最新的已经支持gif 图和添加刷新图片了

 18-->怎么把tableview里cell的小对勾的颜色改成别的颜色？    _mTableView.tintColor = [UIColor redColor];19-->本来我的statusbar是lightcontent的，结果用UIImagePickerController会导致我的statusbar的样式变成黑色，怎么办？- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated{    [[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent];}20-->怎么把我的navigationbar弄成透明的而不是带模糊的效果？    [self.navigationBar setBackgroundImage:[UIImage new]                         forBarMetrics:UIBarMetricsDefault];    self.navigationBar.shadowImage = [UIImage new];    self.navigationBar.translucent = YES;21-->怎么改变uitextfield placeholder的颜色和位置？   继承uitextfield，重写这个方法- (void) drawPlaceholderInRect:(CGRect)rect {    [[UIColor blueColor] setFill];    [self.placeholder drawInRect:rect withFont:self.font lineBreakMode:UILineBreakModeTailTruncation alignment:self.textAlignment];}22-->如何修改导航返回按钮的标题（默认是上一级导航的title） ？    // 推到下个页面之前 修改backItem标题为返回    UIBarButtonItem *backBtn = [[UIBarButtonItem alloc] init];    backBtn.title = @"返回";    self.navigationItem.backBarButtonItem = backBtn;    [self.navigationController pushViewController:zhtVC animated:YES];