iOS应用程序：定位后调整图像的尺寸

Question

因为我确定我的答案已经存在，所以我会事先致歉，但在尝试了很多建议之后，我似乎无法让我的应用程序正常工作。

基本上，我想以相同的比例显示一个16x9的图像到屏幕中央的全部宽度。与纵向相比，横向的图像将更大。我可以显示图像，但是当我的Ipad旋转到纵向时，它会剪切图像的两侧，使图像保持原始高度。我没有使用布局编辑器，并且不希望为我的第一个应用程序。图像使用下面的代码加载。

viewController.h：

@interface ViewController : UIViewController 
{ 
    UIImageView* MobileImage; // image on mobile device 
} 
@property (nonatomic, retain) UIImageView* MobileImage; 
@end 

viewController.m：

#import "ViewController.h" 

@interface ViewController() 
@end 

@implementation ViewController 

@synthesize MobileImage; 

- (void)viewDidLoad { 
    [super viewDidLoad]; 

    CGFloat width = self.view.bounds.size.width; 
    CGFloat height = width * 9/16; 
    if (height > self.view.bounds.size.height) { // just in case 
     height = self.view.bounds.size.height; 
     width = height * 16/9; 
    } 
    self.MobileImage = [[UIImageView alloc] initWithFrame:CGRectMake(0.0, 0.0, width, height)]; 
    self.MobileImage.image = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"sandy-ralph" ofType:@"png"]]; 
    self.MobileImage.center = self.view.center; 
    self.MobileImage.autoresizingMask = UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleBottomMargin | UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleRightMargin; 
    self.MobileImage.autoresizesSubviews = YES; 

    [self.view addSubview:self.MobileImage]; 
} 

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

@end 

这工作得很好，如果我不关心剪辑（假设我在景观开始​​，旋转为纵向）。我插入我试图调整它下面的代码到执行的viewController：

- (void)viewWillTransitionToSize:(CGSize)size withTransitionCoordinator:(id<UIViewControllerTransitionCoordinator>)coordinator 
{ 
    [super viewWillTransitionToSize:size withTransitionCoordinator:coordinator]; 

    NSLog(@"Transition to size = %@", NSStringFromCGSize(size)); 
    CGFloat width = size.width; 
    CGFloat height = width * 9/16; 
    if (height > size.height) { // just in case 
     height = size.height; 
     width = height * 16/9; 
    } 

#if 1 // this code has no effect on the image size 
    NSLog(@"Using UIGraphicsGetImageFromCurrentImageContext"); 
    UIGraphicsBeginImageContextWithOptions(CGSizeMake(width, height), NO, 0.0); 
    CGContextRef context = UIGraphicsGetCurrentContext(); 
    UIGraphicsPushContext(context); 
    [self.MobileImage.image drawInRect:CGRectMake(0, 0, width, height)]; 
    UIGraphicsPopContext(); 
    UIImage *newimage = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 

    NSUInteger i1 = [self.view.subviews indexOfObject:self.MobileImage]; 
    UIView *superview = self.MobileImage.superview; 
    [self.MobileImage removeFromSuperview]; 
    self.MobileImage.image = newimage; 
    [superview insertSubview:self.MobileImage atIndex:i1]; 
#else // the code resizes but causes image to sit on bottom of screen 
    NSLog(@"Using CGRectMake"); 
    self.MobileImage.frame = CGRectMake(0.0, 0.0, width, height); 
#if 1 // With/without next three lines, image still sits on bottom of screen 
    self.MobileImage.center = CGPointMake(width/2, height/2); 
    self.MobileImage.autoresizingMask = UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleBottomMargin | UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleRightMargin; 
    self.MobileImage.autoresizesSubviews = YES; 
#endif 
#endif 
} 

预处理指令是用于测试不同的代码。使用“#if 1”，没有调整大小。使用“#if 0”，它会调整大小，但位于底部，无论代码是否居中。我认为这是一个小小的解决方案，但我已经试用和测试，比我妻子可以容忍的时间长（即忽略“待办事项列表”），没有任何进展，我认为该是寻求帮助的时候了。预先感谢您的帮助。

Answer 1

要获得新的宽度和高度，使用这样的：

- (void)viewWillTransitionToSize:(CGSize)size withTransitionCoordinator:(id<UIViewControllerTransitionCoordinator>)coordinator 
{ 
    [super viewWillTransitionToSize:size withTransitionCoordinator:coordinator]; 
    CGFloat screenWidth = size.width; 
    CGFloat screenHeight = size.height; 


    UIImage* image = self.MobileImage.image; 
    CGFloat mobileImageWidth = image.size.width; 
    CGFloat mobileImageHeight = image.size.height; 

    CGFloat newMobileImageWidth = 0; 
    CGFloat newMobileImageHeight = 0; 

    double widthRatio = mobileImageWidth/screenWidth; 
    double heightRatio = mobileImageHeight/screenHeight; 

    if (widthRatio < heightRatio) { 
     newMobileImageHeight = screenHeight; 
     newMobileImageWidth = screenWidth/widthRatio; 
    } 
    else { 
     newMobileImageWidth = screenWidth; 
     newMobileImageHeight = screenHeight/heightRatio; 
    } 

    //use these new width and height for your image 

} 

Answer 2

好了，想通了，我需要的东西，使其工作。不知道这是否是最好的方式，但对我的测试程序来说已经足够了。此外，不再需要自动调整。如果别人有同样的问题，现在该代码的样子：

- (void)viewDidLoad { 
    [super viewDidLoad]; 

    CGFloat viewheight = self.view.bounds.size.height - [[UIApplication sharedApplication] statusBarFrame].size.height; 
    CGFloat width = self.view.bounds.size.width; 
    CGFloat height = width * 9/16; 
    if (height > viewheight) { // don't exceed viewable height 
     height = viewheight; 
     width = height * 16/9; 
    } 
    self.MobileImage = [[UIImageView alloc] initWithFrame:CGRectMake(0.0, 0.0, width, height)]; 
    self.MobileImage.image = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"sandy-ralph" ofType:@"png"]]; 
    self.MobileImage.center = self.view.center; 

    [self.view addSubview:MobileImage]; 
} 

- (void)viewWillTransitionToSize:(CGSize)size withTransitionCoordinator:(id<UIViewControllerTransitionCoordinator>)coordinator 
{ 
    [super viewWillTransitionToSize:size withTransitionCoordinator:coordinator]; 

    CGFloat statusbarheight = [[UIApplication sharedApplication] statusBarFrame].size.height; 
    CGFloat viewheight = size.height - statusbarheight; 
    CGFloat width = size.width; 
    CGFloat height = width * 9/16; 
    if (height > viewheight) { // don't exceed viewable height 
     height = viewheight; 
     width = height * 16/9; 
    } 

    CGRect frame = self.MobileImage.frame; 
    frame.size.width = width; 
    frame.size.height = height; 
    frame.origin.x = (size.width - width)/2; 
    frame.origin.y = statusbarheight + (viewheight - height)/2; 
    self.MobileImage.frame = frame; 
}