The app delegate must implement the window property if it wants to use a main storyboard file.
在AppDelegate.m
#import "AppDelegate.h"
@interface AppDelegate ()
@end
@implementation AppDelegate
@synthesize window = _window;
The app delegate must implement the window property if it wants to use a main storyboard file.
在AppDelegate.m
#import "AppDelegate.h"
@interface AppDelegate ()
@end
@implementation AppDelegate
@synthesize window = _window;
#include 區分 #include <x.h>與#include "x.h"的作用 #include <x.h>:它用於對系統自帶的頭文件的引用,編譯器會在系統文件目錄下去查找該文件.