UI --- UIView 畫圓和矩形

矩形

1. 以 window 爲父視圖

for (int i = 0; i < 6; i++) {
     UIView *subView = [[UIView alloc] initWithFrame:CGRectMake((self.window.frame.size.width - 280 + 40 * i) / 2, (self.window.frame.size.height - 480 + 80 * i) / 2, 280 - 40 * i, 480 - 80 * i)];
     subView.backgroundColor = [UIColor colorWithRed:(1.0 - 0.15 * i) green:(1.0 - 0.1 * i) blue:(1.0 - 0.1 * i) alpha:1.0];
    [self.window addSubview:subView];
    [subView release];
}

2. 以前一個視圖爲父視圖

UIView *fatherView = self.window;
for (int i = 0; i < 6; i++) {
    UIView *subView = [[UIView alloc] initWithFrame:CGRectMake((fatherView.bounds.size.width - 280 + 40 * i) / 2, (fatherView.bounds.size.height - 480 + 80 * i) / 2, 280 - 40 * i, 480 - 80 * i)];
    subView.backgroundColor = [UIColor colorWithRed:(1.0 - 0.15 * i) green:(1.0 - 0.1 * i) blue:(1.0 - 0.1 * i) alpha:1.0];
    [fatherView addSubview:subView];
    fatherView = subView;
    [subView release];
}

圓

1. 以 window 爲父視圖

for (int i = 0; i < 6; i++) {
    UIView *subView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 280 - 40 * i, 280 - 40 * i)];
    CGPoint center;
    center.x = self.window.frame.size.width / 2;
    center.y = self.window.frame.size.height / 2;
    subView.center = center;
    subView.layer.cornerRadius = (280 - 40 * i) / 2;
    subView.backgroundColor = [UIColor colorWithRed:(1.0 - 0.1 * i) green:(1.0 - 0.15 * i) blue:(1.0 - 0.1 * i) alpha:1.0];
    [self.window addSubview:subView];
    [subView release];
}

2. 以前一個視圖爲父視圖

UIView *fatherView = self.window;
for (int i = 0; i < 6; i++) {
    UIView *subView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 280 - 40 * i, 280 - 40 * i)];
    CGPoint center;
    center.x = fatherView.frame.size.width / 2;
    center.y = fatherView.frame.size.height / 2;
    subView.center = center;
    subView.layer.cornerRadius = (280 - 40 * i) / 2;
    subView.backgroundColor = [UIColor colorWithRed:(1.0 - 0.15 * i) green:(1.0 - 0.1 * i) blue:(1.0 - 0.1 * i) alpha:1.0];
    [fatherView addSubview:subView];
    fatherView = subView;
    [subView release];
}

補充
獲取隨機色:
subView.backgroundColor = [UIColor colorWithRed:(arc4random() % 256 )/(255 * 1.0) green:(arc4random() % 256)/(255 * 1.0) blue:(arc4random() % 256)/(255 * 1.0) alpha:1.0];