UI2_IOS坐标系

            //
            //
              AppDelegate.m

            //
              UI2_IOS坐标系

            //
            //
              Created by zhangxueming on 15/6/29.

            //
              Copyright (c) 2015年 zhangxueming. All rights reserved.

            //

            #import
            "
            AppDelegate.h
            "
            @interface
             AppDelegate ()


            @end
            @implementation
             AppDelegate


- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.
    
    
    //window的默认颜色是透明色
    self.window.backgroundColor = [UIColor whiteColor];
    //NSLog(@"window = %@", self.window);
    NSLog(@"x = %.2f y=%.2f w = %.2f h = %.2f",self.window.frame.origin.x, self.window.frame.origin.y, self.window.frame.size.width, self.window.frame.size.height);
    //ios坐标系
    //frame坐标: 相对于父视图的坐标
    //bounds坐标:ios坐标(起始点从(0,0)开始)
    
    //状态栏的高度是20    
    CGRect frame = [[UIScreen mainScreen] bounds];
    NSLog(@"x = %.2f y = %.2f w= %.2f h = %.2f", frame.origin.x, frame.origin.y, frame.size.width, frame.size.height);
    
    UIWindow *window1 = [[UIWindow alloc] initWithFrame:CGRectMake(10, 50, self.window.frame.size.width-20, self.window.frame.size.height-100)];
    window1.backgroundColor = [UIColor cyanColor];
    
    [self.window addSubview:window1];
    
    //使window1在最上层显示    [window1 makeKeyAndVisible];
    
    //通常一个应用程序有一个Window(窗口)
    //相当于一个容器
    UIView *view1 = [[UIView alloc] initWithFrame:CGRectMake(20, 100, self.window.frame.size.width-40, 50)];
    view1.backgroundColor = [UIColor redColor];
    
    [self.window addSubview:view1];
    
    //view1的retainCount加1
    //NSLog(@"retainCount = %li", view1.retainCount);    
    self.window.rootViewController = nil;
    return YES;
}