iOS程序启动原理(简单)

 1 int main(int argc, char * argv[]) {
 2     NSString *filePath = [[NSBundle mainBundle] pathForResource:@"Info.plist" ofType:nil];
 3     NSDictionary *dcit = [NSDictionary dictionaryWithContentsOfFile:filePath];
 4     id objc = dcit[@"UIMainStoryboardFile"];
 5    
 6     @autoreleasepool {
 7          第三个参数:UIApplication类或者子类类型字符串,类型不能乱穿
 8          第四个参数:UIApplication代理类型字符串类型不能乱穿
 9          NSStringFromClass([AppDelegate class])
10          NSStringFromClass:把类名转换成字符串
11         return UIApplicationMain(argc, argv, @"UIApplication", NSStringFromClass([AppDelegate class]));
12          如果直接写字符串,弊端:有可能写错,没有提示
13          NSStringFromClass:有提示,肯定不会写错,编译时期就会检查错误
14        
15     }
16 }