Swift中的catch异常的一种写法。
do {
let results = try managedContext.execute(fetchRequest)
} catch let error as NSError { }
然后在下面就可以catch到error了~
viewWillAppear不执行的解决办法
UITableViewController或UIViewController中使() 后viewWillAppear:(BOOL)animated不执行 解决方法如下： 先在 *.h 头文件里加上<UINavigationControllerDelegate> 接着在*.m 文件里加上相关代码 self.navigationController.delegate=self; 再使用此时navigationController的代理函数，就OK了。 -(void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated { [viewController viewWillAppear:animated]; } -(void)viewWillAppear:(BOOL)animated { NSLog(@"现在可以使用了"); } 代码实例： MyOrders.h @interface MyOrders : UIViewControllerlegate>{ } @property(nonatomic,retain)IBOutlet UITableView *table; MyOrders.m - (void)viewDidLoad { [super viewDidLoad]; self.navigationController.delegate=self; } -(void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated { [viewController viewWillAppear:animated]; } -(void)viewWillAppear:(BOOL)a...
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