开发的21个奇葩技巧
- TableView不显示没内容的Cell怎么办？
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， - 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<UI)
- ScrollView莫名其妙不能在viewController划到顶怎么办？
self.automaticallyAdjustsScrollViewInsets = NO;
- 键盘事件写得好烦躁，都想摔键盘了怎么办？
使用IQKeyboardManager（GitHub上可搜索）
- 为什么我的App老是不流畅，到底哪里出了问题？
KMCGeigerCounter ，快去GitHub上搬运吧
- 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？
[self.view endEditing:YES];
- 怎么给每个ViewController设定默认的背景图片？
使用基类啊
- 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。
- 怎么像Safari一样滑动的时候隐藏navigationbar？
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？
MagicRecord
- 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？
UIImage *image = [[UIImage imageNamed:@"xxx"] stretchableImageWithLeftCapWidth:10 topCapHeight:10];
注：有开发者提醒这个已经弃用，现在的方法叫
resizableImageWithCapInsets。
- 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。
- 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];
- 怎么把tableview里Cell的小对勾颜色改成别的颜色？
_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];
}
```