iOS开发的22个奇葩技巧

. TableView不显示没内容的Cell怎么办?

类似于图1,我不想让下面的那些空显示。很简单,添加“self.tableView.tableFooterView = [[UIView alloc] init];”试过都说好,加完这句之后就变成了图2的样子。
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

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3. ScrollView莫名其妙不能在viewController划到顶怎么办?


**self.automaticallyAdjustsScrollViewInsets = NO; **

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4. 键盘事件写得好烦躁,都想摔键盘了怎么办?

买个结实的键盘;
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?

如图:

iOS开发的22个奇葩技巧_第1张图片

这个神器叫做:KMCGeigerCounter
,快去GitHub上搬运吧。
6. 怎么在不新建一个Cell的情况下调整separaLine的位置?


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

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7. 怎么点击self.view就让键盘收起,需要添加一个tapGestures么?

  • (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
    {
    [self.view endEditing:YES];
    }

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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,但该怎么用代码找?

像拉Button一样地拉你的约束,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 = Yes

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11. 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];**

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12. CoreData用起来好烦,语法又臭又长怎么办?

MagicRecord

13. CollectionView怎么实现tableview那种悬停的header?

CSStickyHeaderFlowLayout

14. 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; **

**} **

**} **

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15. 拉伸图片的时候怎么才能让图片不变形?

方法一:

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

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注:有开发者提醒这个已经弃用,现在的方法叫resizableImageWithCapInsets。

方法二,如图:

iOS开发的22个奇葩技巧_第2张图片

16. 怎么播放GIF的时候这么卡,有没有好点的库?

FlipBoard出品的FLAnimatedImage太适合你了。

17. 怎么一句话添加上拉刷新?

使用SVPullToRefresh库:

[tableView addPullToRefreshWithActionHandler:^{

// prepend data to dataSource, insert cells at top of table view

// call [tableView.pullToRefreshView stopAnimating] when done

} position:SVPullToRefreshPositionBottom];

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18. 怎么把tableview里Cell的小对勾颜色改成别的颜色?


**_mTableView.tintColor = [UIColor redColor]; **

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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]; **

**} **

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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; **

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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];
    }

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