----------UI窗口于视图的创建示例----------

在window上创建赤橙黄绿青蓝紫七个视图，互相嵌套，设置定时器，每秒每个视图随机变换颜色，并且旋转，十秒后停止，视图全部移除。

---AppDelegate.h中声明视图和一个计时的变量

@interface AppDelegate : UIResponder <UIApplicationDelegate>

{

UIView *view1;

UIView *view2;

UIView *view3;

UIView *view4;

UIView *view5;

UIView *view6;

UIView *view7;

int second;

}

---AppDelegate.m中实现题中要求

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

CGRect rect = [UIScreen mainScreen].bounds;

//创建主Window

self.window = [[UIWindow alloc]initWithFrame:rect];

self.window.backgroundColor = [UIColor blackColor];

[self.window makeKeyAndVisible];

//创建View

view1 = [[UIView alloc]initWithFrame:CGRectMake(70, 70, 250, 250)];

view1.backgroundColor= [UIColor redColor];

view1.tag = 1;

view2 = [[UIView alloc]initWithFrame:CGRectMake(15, 15, 220, 220)];

view2.backgroundColor= [UIColor orangeColor];

view3 = [[UIView alloc]initWithFrame:CGRectMake(15, 15, 190, 190)];

view3.backgroundColor= [UIColor yellowColor];

view4 = [[UIView alloc]initWithFrame:CGRectMake(15, 15, 160, 160)];

view4.backgroundColor= [UIColor greenColor];

view5 = [[UIView alloc]initWithFrame:CGRectMake(15, 15 , 130, 130)];

view5.backgroundColor= [UIColor cyanColor];

view6 = [[UIView alloc]initWithFrame:CGRectMake(15, 15, 100, 100)];

view6.backgroundColor= [UIColor blueColor];

view7 = [[UIView alloc]initWithFrame:CGRectMake(25, 25, 50, 50)];

view7.backgroundColor= [UIColor purpleColor];

[self.window addSubview:view1];

[view1 addSubview:view2];

[view2 addSubview:view3];

[view3 addSubview:view4];

[view4 addSubview:view5];

[view5 addSubview:view6];

[view6 addSubview:view7];

second = 10;

//定时器

[NSTimer scheduledTimerWithTimeInterval:1

target:self

selector:@selector(timeAction:)

userInfo:nil

repeats:YES];

return YES;

}

- (void)timeAction:(NSTimer *)timer{

//七个视图颜色随机变

view1.backgroundColor = [UIColor colorWithRed:(arc4random()%255/255.0) green:(arc4random()%255/255.0) blue:(arc4random()%255/255.0) alpha:1];

view2.backgroundColor = [UIColor colorWithRed:(arc4random()%255/255.0) green:(arc4random()%255/255.0) blue:(arc4random()%255/255.0) alpha:1];

view3.backgroundColor = [UIColor colorWithRed:(arc4random()%255/255.0) green:(arc4random()%255/255.0) blue:(arc4random()%255/255.0) alpha:1];

view4.backgroundColor = [UIColor colorWithRed:(arc4random()%255/255.0) green:(arc4random()%255/255.0) blue:(arc4random()%255/255.0) alpha:1];

view5.backgroundColor = [UIColor colorWithRed:(arc4random()%255/255.0) green:(arc4random()%255/255.0) blue:(arc4random()%255/255.0) alpha:1];

view6.backgroundColor = [UIColor colorWithRed:(arc4random()%255/255.0) green:(arc4random()%255/255.0) blue:(arc4random()%255/255.0) alpha:1];

view7.backgroundColor = [UIColor colorWithRed:(arc4random()%255/255.0) green:(arc4random()%255/255.0) blue:(arc4random()%255/255.0) alpha:1];

//旋转

UIView *view = [self.window viewWithTag:1];

CGAffineTransform trans = view.transform;

view.transform = CGAffineTransformRotate(trans, M_PI/10);

//十秒后计时器停止，视图移除

second--;

if (second < 0) {

[timer invalidate];

[view1 removeFromSuperview];

return;

}

}