- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    //使用图片初始化背景色
    self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"gradient2"]];
    //实现模糊效果
    UIVisualEffectView *visualEffectView = [[UIVisualEffectView alloc] initWithEffect:[UIBlurEffect effectWithStyle:UIBlurEffectStyleLight]];
    visualEffectView.frame = self.view.bounds;
    visualEffectView.alpha = 1.0;
    [self.view addSubview:visualEffectView];
}

效果对比