ios开发——视图动画

#import "ViewController.h"

@interface ViewController () {
    //小球运动方向标志，1表示向下运行，-1表示向上运行
    int flag;
}

@property(strong, nonatomic) UIImageView *ball;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    //初始化小球运动方向标志
    flag = 1;
    
    //界面初始化
    CGRect screen = [[UIScreen mainScreen] bounds];

    CGFloat imageWidth = 86;
    CGFloat imageHeight = 86;
    CGFloat imageTopView = 150;
    CGRect imageFrame = CGRectMake((screen.size.width - imageWidth) / 2, imageTopView, imageWidth, imageHeight);
    //创建Image View对象
    self.ball = [[UIImageView alloc] initWithFrame:imageFrame];
    //设置Image View的图片属性
    self.ball.image = [UIImage imageNamed:@"Ball.png"];
    //添加Image View到当前视图
    [self.view addSubview:self.ball];

    //创建按钮对象
    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    //设置按钮正常状态时显示图片
    [button setImage:[UIImage imageNamed:@"ButtonOutline.png"] forState:UIControlStateNormal];
    //设置按钮高亮状态时显示图片
    [button setImage:[UIImage imageNamed:@"ButtonOutlineHighlighted.png"] forState:UIControlStateHighlighted];
    //设置按钮触摸动作输出口
    [button addTarget:self action:@selector(onClick:) forControlEvents:UIControlEventTouchUpInside];

    CGFloat buttonWidth = 130;
    CGFloat buttonHeight = 50;
    CGFloat buttonTopView = 500;
    button.frame = CGRectMake((screen.size.width - buttonWidth) / 2, buttonTopView, buttonWidth, buttonHeight);
    //添加按钮到当前视图
    [self.view addSubview:button];

}

- (void)onClick:(id)sender {

    [UIView animateWithDuration:1.5 animations:^{
        CGRect frame = self.ball.frame;
        frame.origin.y += 200 * flag;
        flag *= -1; //取反
        self.ball.frame = frame;
    }];
}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}


@end