#import "ViewController.h"  @interface ViewController ()  @property (weak, nonatomic) IBOutlet UIImageView *backgroundView; @property (strong,nonatomic) NSArray *array;  @end  @implementation ViewController  -(NSArray *)array {   if (_array == nil) {     UIImage *image1 = [UIImage imageNamed:@"01.jpg"];     UIImage *image2 = [UIImage imageNamed:@"02.jpg"];     _array = @[image1,image2];   }   return _array; }  - (void)viewDidLoad {   [super viewDidLoad];   self.backgroundView.image = self.array[0];   // Do any additional setup after loading the view, typically from a nib. }  -(void)changeImage {   if (self.backgroundView.image == self.array[0]) {     self.backgroundView.image = self.array[1];   }else {     self.backgroundView.image = self.array[0];   } }  - (IBAction)pushClick:(id)sender {   [self changeImage];   CATransition *transtion = [[CATransition alloc] init];   transtion.type = @"push";   transtion.subtype = kCATransitionFromBottom;   transtion.startProgress = 0.5;   transtion.endProgress = 0.8;   [self.view.layer addAnimation:transtion forKey:nil]; }  /*  效果有好多種，上面代碼只貼出了其中一種，如果需要其他效果，只需要將  transtion.type = @"push";中的type改一下就行。  比如：  transtion.type = @"fade";  type的類型還有以下幾種：  fade，reveal，moveIn，cube，suckEffect，oglFlip，rippleEffect，pageCurl，pageCurl，cameraIrisHollowOpen，cameraIrisHollowClose，pageUnCurl，pageCurl，pageCurl，pageCurl   */  - (void)didReceiveMemoryWarning {   [super didReceiveMemoryWarning];   // Dispose of any resources that can be recreated. }