1、禁止手机睡眠
[UIApplication sharedApplication].idleTimerDisabled = YES;
2、隐藏某行cell
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
if(indexPath.row == YouWantToHideRow) return 0;
return 44;
[self.tableView beginUpdates];
[self.tableView endUpdates];
}
3、禁用button高亮
button.adjustsImageWhenHighlighted = NO;
或者在创建的时候
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
4、tableview遇到这种报错failed to obtain a cell from its dataSource
是因为你的cell被调用的早了。先循环使用了cell,后又创建cell。顺序错了
可能原因:
1、xib的cell没有注册
2、内存中已经有这个cell的缓存了(也就是说通过你的cellId找到的cell并不是你想要的类型),这时候需要改下cell的标识
5、动画切换window的根控制器
// options是动画选项
[UIView transitionWithView:[UIApplication sharedApplication].keyWindow duration:0.5f options:UIViewAnimationOptionTransitionCrossDissolve animations:^{
BOOL oldState = [UIView
areAnimationsEnabled];
[UIView setAnimationsEnabled:NO];
[UIApplication sharedApplication].keyWindow.rootViewController = [RootViewController new];
[UIView setAnimationsEnabled:oldState];
} completion:^(BOOL finished) {
}];
6、去除数组中重复的对象
NSArray *newArr = [oldArr valueForKeyPath:@“@distinctUnionOfObjects.self"];
7、编译的时候遇到 no such file or directory: /users/apple/XXX
是因为编译的时候,在此路径下找不到这个文件,解决这个问题,首先是是要检查缺少的文件是不是在工程中,如果不在工程中,需要从本地拖进去,如果发现已经存在工程中了,或者拖进去还是报错,这时候需要去build phases中搜索这个文件,这时候很可能会搜出现两个相同的文件,这时候,有一个路径是正确的,删除另外一个即可。如果删除了还是不行,需要把两个都删掉,然后重新往工程里拖进这个文件即可
image
8、iOS8系统中,tableView最好实现下-tableView: heightForRowAtIndexPath:这个代理方法,要不然在iOS8中可能就会出现显示不全或者无法响应事件的问题
9、给一个view截图
UIGraphicsBeginImageContextWithOptions(view.bounds.size, YES, 0.0);
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
10、开发中如果要动态修改tableView的tableHeaderView或者tableFooterView的高度,需要给tableView重新设置,而不是直接更改高度。正确的做法是重新设置一下tableView.tableFooterView = 更改过高度的view。为什么?其实在iOS8以上直接改高度是没有问题的,在iOS8中出现了contentSize不准确的问题,这是解决办法。
11、注意对象为nil的时候,调用此对象分类的方法不会执行
12、collectionView的内容小于其宽高的时候是不能滚动的,设置可以滚动:
collectionView.alwaysBounceHorizontal = YES;
collectionView.alwaysBounceVertical = YES;
13、由角度转换弧度
#define DegreesToRadian(x) (M_PI * (x) / 180.0)
14、由弧度转换角度
#define RadianToDegrees(radian) (radian*180.0)/(M_PI)
15、获取图片资源
#define GetImage(imageName) [UIImage imageNamed:[NSString stringWithFormat:@"%@",imageName]]
16、获取window
+(UIWindow*)getWindow {
UIWindow* win = nil;
for (id item in [UIApplication sharedApplication].windows) {
if ([item class] == [UIWindow class]) {
if (!((UIWindow*)item).hidden) {
win = item;
break;
}
}
}
return win;
}
17、修改textField的placeholder的字体颜色、大小
- [textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];
- [textField setValue:[UIFont boldSystemFontOfSize:16] forKeyPath:@"_placeholderLabel.font"];
18、统一收起键盘
[[[UIApplication sharedApplication] keyWindow] endEditing:YES];
19、获取app缓存大小
- (CGFloat)getCachSize {
NSUInteger imageCacheSize = [[SDImageCache sharedImageCache] getSize];
NSString *myCachePath = [NSHomeDirectory() stringByAppendingPathComponent:@"Library/Caches"];
NSDirectoryEnumerator *enumerator = [[NSFileManager defaultManager] enumeratorAtPath:myCachePath];
__block NSUInteger count = 0;
for (NSString *fileName in enumerator) {
NSString *path = [myCachePath stringByAppendingPathComponent:fileName];
NSDictionary *fileDict = [[NSFileManager defaultManager] attributesOfItemAtPath:path error:nil];
count += fileDict.fileSize;
}
CGFloat totalSize = ((CGFloat)imageCacheSize+count)/1024/1024;
return totalSize;
}
20、清理app缓存
- (void)handleClearView {
[[SDImageCache sharedImageCache] clearMemory];
[[SDImageCache sharedImageCache] clearDisk];
NSString *myCachePath = [NSHomeDirectory() stringByAppendingPathComponent:@"Library/Caches"];
[[NSFileManager defaultManager] removeItemAtPath:myCachePath error:nil];
}
21、打印百分号和引号
NSLog(@"%%");
NSLog(@"\"");
22、几个常用权限判断
if ([CLLocationManager authorizationStatus] ==kCLAuthorizationStatusDenied) {
NSLog(@"没有定位权限");
}
AVAuthorizationStatus statusVideo = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
if (statusVideo == AVAuthorizationStatusDenied) {
NSLog(@"没有摄像头权限");
}
AVAuthorizationStatus statusAudio = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeAudio];
if (statusAudio == AVAuthorizationStatusDenied) {
NSLog(@"没有录音权限");
}
[PHPhotoLibrary requestAuthorization:^(PHAuthorizationStatus status) {
if (status == PHAuthorizationStatusDenied) {
NSLog(@"没有相册权限");
}
}];
23、长按复制功能
- (void)viewDidLoad {
[self.view addGestureRecognizer:[[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(pasteBoard:)]];
}
- (void)pasteBoard:(UILongPressGestureRecognizer *)longPress {
if (longPress.state == UIGestureRecognizerStateBegan) {
UIPasteboard *pasteboard = [UIPasteboard generalPasteboard];
pasteboard.string = @"需要复制的文本";
}
}
24、cocoapods升级
在终端执行 sudo gem install -n / usr / local / bin cocoapods --pre
更新cocoapods本地仓库 $ pod repo update
pod库搜索不到SDK,删除索引
rm ~/Library/Caches/CocoaPods/search_index.json,再搜索一次
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