完全靠代码生成的ios版hello,world

xcode5 运行在iphone retain 3.5" 模式下（即对应iphone4, iphone4s）需要开启ARC

//

//  main.m

//  Hello

//

//  Created by lishujun on 14-8-28.

//  Copyright (c) 2014年 lishujun. All rights reserved.

//



#import <UIKit/UIKit.h>





// 视图控制器对象

@interface HelloWorldViewController : UIViewController

@end



@implementation HelloWorldViewController



-(void) loadView

{

    //创建视图对象

    UIView *contentView = [[UIView alloc]initWithFrame:[[UIScreen mainScreen] applicationFrame]];

    contentView.backgroundColor = [UIColor lightGrayColor];

    self.view = contentView;

    

    //创建label对象

    UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(0.0, 0.0, 320.0, 30.0)];

    label.text = @"Hello World";

    label.center = contentView.center;             // 垂直居中

    label.textAlignment = UITextAlignmentCenter;   // 水平居中

    label.backgroundColor = [UIColor clearColor];

    label.textColor = [UIColor redColor];

    

    //在视图上添加label

    [contentView addSubview:label];

}



@end





// 委托对象

@interface HelloWorldAppDelegate : NSObject <UIApplicationDelegate>

{

    IBOutlet UIWindow *window;

}



@property (nonatomic, retain) UIWindow *window;

//必须声明为属性,声明为局部变量则无法绘制视图，显示为黑屏

@end



@implementation HelloWorldAppDelegate

@synthesize window;



-(void) applicationDidFinishLaunching:(UIApplication *)application

{

    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen]bounds]];

    HelloWorldViewController *viewController = [[HelloWorldViewController alloc]init];

    self.window.rootViewController = viewController;

    [self.window makeKeyAndVisible];

}



@end



// 程序入口

int main(int argc, char * argv[])

{

    @autoreleasepool {

        return UIApplicationMain(argc, argv, nil, @"HelloWorldAppDelegate");

    }

}