(转） iOS开发的一些奇巧淫技

 转自：http://blog.csdn.net/dwarven/article/details/42388711

 

TableView不显示没内容的Cell怎么办?

类似这种,我不想让下面那些空的显示.

 

很简单.

 

 

    self.tableView.tableFooterView = [[UIView alloc] init];  

 

试过的都说好.


加完这句之后就变成了这样.

 

 

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;  

  

 

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

self.automaticallyAdjustsScrollViewInsets = NO; 

 

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.

为什么我的app老是不流畅,到底哪里出了问题?

如图

 

 

这个神器叫做:KMCGeigerCounter,快去github搬运吧.


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);

 

 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];  
    }  

 

怎么给每个ViewController设定默认的背景图片?

使用基类啊,少年。

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.

怎么像safari一样滑动的时候隐藏navigationbar?

 

self.navigationController.hidesBarsOnSwipe = YES;

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];  

  

CoreData用起来好烦,语法又臭又长,怎么办?

Magical Record https://github.com/magicalpanda/MagicalRecord

CollectionView 怎么实现tableview那种悬停的header?

CSStickyHeaderFlowLayout

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;  
    }  
    }  

 

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.

 

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：https://github.com/Flipboard/FLAnimatedImage

 

怎么一句话添加上拉刷新？

 

https://github.com/samvermette/SVPullToRefresh

[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的小对勾的颜色改成别的颜色？

_mTableView.tintColor = [UIColor redColor]; 

 

 

 

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];  
    }  

 

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; 

 

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];  
    }