開發(fā)的21個奇葩技巧

• TableView不顯示沒內(nèi)容的Cell怎么辦澎粟？
  我不想讓下面的那些空顯示。很簡單翼雀，添加“self.tableView.tableFooterView = [[UIView alloc] init];”試過都說好，
• 自定義了leftBarbuttonItem左滑返回手勢失效了怎么辦？

self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]initWithImage:img
              style:UIBarButtonItemStylePlain
              target:self
            action:@selector(onBack:)];
self.navigationController.interactivePopGestureRecognizer.delegate = (id<UI)

• ScrollView莫名其妙不能在viewController劃到頂怎么辦坑夯？

self.automaticallyAdjustsScrollViewInsets = NO;

• 鍵盤事件寫得好煩躁，都想摔鍵盤了怎么辦抡四？

使用IQKeyboardManager（GitHub上可搜索）

• 為什么我的App老是不流暢柜蜈，到底哪里出了問題？

KMCGeigerCounter 指巡，快去GitHub上搬運吧

• 怎么在不新建一個Cell的情況下調(diào)整separaLine的位置淑履？

_myTableView.separatorInset = UIEdgeInsetsMake(0, 100, 0, 0);

• 怎么點擊self.view就讓鍵盤收起，需要添加一個tapGestures么藻雪？

[self.view endEditing:YES];

• 怎么給每個ViewController設(shè)定默認的背景圖片秘噪？

使用基類啊

• 想在代碼里改在xib里添加的layoutAttributes，但該怎么用代碼找勉耀？

像拉Button一樣地拉你的約束指煎，nslayoutattribute也是可以拉線的。

• 怎么像Safari一樣滑動的時候隱藏navigationbar便斥？

navigationController.hidesBarsOnSwipe = Yes

• 導航條返回鍵帶的title太討厭了至壤，怎么讓它消失？

[[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60)                                                    forBarMetrics:UIBarMetricsDefault];

• CoreData用起來好煩枢纠，語法又臭又長怎么辦像街？

MagicRecord

• CollectionView怎么實現(xiàn)tableview那種懸停的header？

CSStickyHeaderFlowLayout

• 能不能只用一個pan手勢來代替UISwipegesture的各個方向？

(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;
 }
 }

• 拉伸圖片的時候怎么才能讓圖片不變形镰绎？

UIImage *image = [[UIImage imageNamed:@"xxx"] stretchableImageWithLeftCapWidth:10 topCapHeight:10];

注：有開發(fā)者提醒這個已經(jīng)棄用脓斩，現(xiàn)在的方法叫

resizableImageWithCapInsets。

• 怎么播放GIF的時候這么卡跟狱，有沒有好點的庫俭厚？

FlipBoard出品的FLAnimatedImage太適合你了。

• 怎么一句話添加上拉刷新驶臊？
  使用SVPullToRefresh庫：

 [tableView addPullToRefreshWithActionHandler:^{
// prepend data to dataSource, insert cells at top of table view
// call [tableView.pullToRefreshView stopAnimating] when done
 } position:SVPullToRefreshPositionBottom];

• 怎么把tableview里Cell的小對勾顏色改成別的顏色挪挤？

_mTableView.tintColor = [UIColor redColor];

• 本來我的statusbar是lightcontent的，結(jié)果用UIImagePickerController會導致我的statusbar的樣式變成黑色关翎，怎么辦扛门？

 (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{    [[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent];
}

• 怎么把我的navigationbar弄成透明的而不是帶模糊的效果？

[self.navigationBar setBackgroundImage:[UIImage new]
                          forBarMetrics:UIBarMetricsDefault];
 self.navigationBar.shadowImage = [UIImage new];
 self.navigationBar.translucent = YES;
```
- 怎么改變uitextfield placeholder的顏色和位置纵寝？
繼承uitextfield论寨，重寫這個方法：  
```
 (void) drawPlaceholderInRect:(CGRect)rect {
     [[UIColor blueColor] setFill];
     [self.placeholder drawInRect:rect withFont:self.font lineBreakMode:UILineBreakModeTailTruncation alignment:self.textAlignment];
 }
  ```