1、tableView隐藏无内容的cell

self.tableview.tableviewFooterView = [[UIView alloc] init];

2、tableViewCell 的分割线顶头设置

iOS7:
[self.tableview setSeparatorInset:UIEdgeInsetsZero];
iOS8:

viewDidLoad 添加
 if ([self.tableView respondsToSelector:@selector(setSeparatorInset:)]) {
         [self.tableView setSeparatorInset:UIEdgeInsetsZero];
}
 if ([self.tableView respondsToSelector:@selector(setLayoutMargins:)]) {
         [self.tableView setLayoutMargins:UIEdgeInsetsZero];
}
tableView 代理添加
 - (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
    if ([cell respondsToSelector:@selector(setSeparatorInset:)]) {
        [cell setSeparatorInset:UIEdgeInsetsZero];
    }
    if ([cell respondsToSelector:@selector(setLayoutMargins:)]) {
        [cell setLayoutMargins:UIEdgeInsetsZero];
    }
}

3、自定义了leftBarbuttonItem左滑返回手势失效了

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

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

self.automaticallyAdjustsScrollViewInsets = NO;

5、调整tableView 分割线的位置

self.tableview.separatorInset = UIEdgeInsetsMake(0, x, 0, 0);

6、点击self.view 收起键盘

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

7、怎么像safari一样滑动的时候隐藏navigationbar?

navigationController.hidesBarsOnSwipe = Yes;

8、消除返回按钮的标题

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

9、用一个pan手势来代替UISwipegesture的各个方向(不知道应用场景)

- (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;
    }
}

10、拉伸图片

• UIImage *image = [[UIImage imageNamed:@"xxx"] stretchableImageWithLeftCapWidth:10 topCapHeight:10];
• UIImage *image = [[UIImage imageNamed:@"xxx"] resizableImageWithCapInsets:UIEdgeInsetsMake(10, 10, 10, 10)];
• 九切片技术

九切片

11、用UIImagePickerController导致statusbar的样式变成黑色

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

12、把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;

13、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];
}

14、取消Button按钮的按下的阴影效果

创建button的时候加上下面这句，官方文档说的很清楚。
btn.adjustsImageWhenHighlighted = NO;

结合文章：
iOS 开发一些小技巧