我正在使用Xcode 5的资产目录，我想使用我的LaunchImage作为我家视图的背景图像（这是一种非常常见的做法，可以从'加载'过渡到'加载'看起来很平滑）。
我想在资产目录中使用相同的条目来节省空间，而不必在两个不同的图像集中复制图像。
但是，致电：
UIImage *image = [UIImage imageNamed:@"LaunchImage"]; //returns nil
这是LaunchImage的（几乎）完整列表（不包括没有状态栏的iPad图像）：
在documentation中有明确说明：
“资产目录中的每个集都有一个名称。您可以使用该名称以编程方式加载集合中包含的任何单个图像。要加载图像，请调用UIImage：ImageNamed：方法，传递包含图像的集合的名称“。
使用Pichirichi的列表有助于解决这种不一致。
可以通过一行代码轻松访问Launch image。
UIImage *myAppsLaunchImage = [UIImage launchImage];
请按照以下步骤操作，以实现上述功能。
步骤1.通过创建类别并向其添加以下方法来扩展UIImage类。
+ (UIImage *)launchImage {
NSDictionary *dOfLaunchImage = [NSDictionary dictionaryWithObjectsAndKeys:
@"[email protected]",@"568,320,2,8,p", // ios 8 - iphone 5 - portrait
@"[email protected]",@"568,320,2,8,l", // ios 8 - iphone 5 - landscape
@"[email protected]",@"568,320,2,7,p", // ios 7 - iphone 5 - portrait
@"[email protected]",@"568,320,2,7,l", // ios 7 - iphone 5 - landscape
@"LaunchImage-700-Landscape@2x~ipad.png",@"1024,768,2,7,l", // ios 7 - ipad retina - landscape
@"LaunchImage-700-Landscape~ipad.png",@"1024,768,1,7,l", // ios 7 - ipad regular - landscape
@"LaunchImage-700-Portrait@2x~ipad.png",@"1024,768,2,7,p", // ios 7 - ipad retina - portrait
@"LaunchImage-700-Portrait~ipad.png",@"1024,768,1,7,p", // ios 7 - ipad regular - portrait
@"[email protected]",@"480,320,2,7,p", // ios 7 - iphone 4/4s retina - portrait
@"[email protected]",@"480,320,2,7,l", // ios 7 - iphone 4/4s retina - landscape
@"LaunchImage-Landscape@2x~ipad.png",@"1024,768,2,8,l", // ios 8 - ipad retina - landscape
@"LaunchImage-Landscape~ipad.png",@"1024,768,1,8,l", // ios 8 - ipad regular - landscape
@"LaunchImage-Portrait@2x~ipad.png",@"1024,768,2,8,p", // ios 8 - ipad retina - portrait
@"LaunchImage-Portrait~ipad.png",@"1024,768,1,8,l", // ios 8 - ipad regular - portrait
@"LaunchImage.png",@"480,320,1,7,p", // ios 6 - iphone 3g/3gs - portrait
@"LaunchImage.png",@"480,320,1,7,l", // ios 6 - iphone 3g/3gs - landscape
@"[email protected]",@"480,320,2,8,p", // ios 6,7,8 - iphone 4/4s - portrait
@"[email protected]",@"480,320,2,8,l", // ios 6,7,8 - iphone 4/4s - landscape
@"[email protected]",@"667,375,2,8,p", // ios 8 - iphone 6 - portrait
@"[email protected]",@"667,375,2,8,l", // ios 8 - iphone 6 - landscape
@"[email protected]",@"736,414,3,8,p", // ios 8 - iphone 6 plus - portrait
@"[email protected]",@"736,414,3,8,l", // ios 8 - iphone 6 plus - landscape
nil];
NSInteger width = ([UIScreen mainScreen].bounds.size.width>[UIScreen mainScreen].bounds.size.height)?[UIScreen mainScreen].bounds.size.width:[UIScreen mainScreen].bounds.size.height;
NSInteger height = ([UIScreen mainScreen].bounds.size.width>[UIScreen mainScreen].bounds.size.height)?[UIScreen mainScreen].bounds.size.height:[UIScreen mainScreen].bounds.size.width;
NSInteger os = [[[[[UIDevice currentDevice] systemVersion] componentsSeparatedByString:@"."] objectAtIndex:0] integerValue];
NSString *strOrientation = UIDeviceOrientationIsLandscape([[UIDevice currentDevice] orientation])?@"l":@"p";
NSString *strImageName = [NSString stringWithFormat:@"%li,%li,%li,%li,%@",width,height,(NSInteger)[UIScreen mainScreen].scale,os,strOrientation];
UIImage *imageToReturn = [UIImage imageNamed:[dOfLaunchImage valueForKey:strImageName]];
if([strOrientation isEqualToString:@"l"] && [strImageName rangeOfString:@"Landscape"].length==0) {
imageToReturn = [UIImage rotate:imageToReturn orientation:UIImageOrientationRight];
}
return imageToReturn;
}
步骤2.上述方法应该通过将以下代码添加到同一类别的UIImage中来工作
static inline double radians (double degrees) {return degrees * M_PI/180;}
+ (UIImage *)rotate:(UIImage*)src orientation:(UIImageOrientation) orientation {
UIGraphicsBeginImageContext(src.size);
CGContextRef context = UIGraphicsGetCurrentContext();
if (orientation == UIImageOrientationRight) {
CGContextRotateCTM (context, radians(90));
} else if (orientation == UIImageOrientationLeft) {
CGContextRotateCTM (context, radians(-90));
} else if (orientation == UIImageOrientationDown) {
// NOTHING
} else if (orientation == UIImageOrientationUp) {
CGContextRotateCTM (context, radians(90));
}
[src drawAtPoint:CGPointMake(0, 0)];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
我意识到这对于每个人来说不一定是最好的解决方案，但最容易（并且最不容易出错，恕我直言）这样做的方法是在Images.xcassets目录中创建一个单独的条目。我叫它SplashImage。
当您添加新条目时，请确保不要选择“新启动图像”作为选项。而是选择通用的“新图像集”。接下来，打开检查器并选择相关选项。如果您只为视网膜设备构建，就像我一样，您可以选择以下内容：
这将为您留下四个条目（iPhone 4S，iPhone 5（s，c），iPhone 6和iPhone 6 Plus）。
对应图像的文件如下：
| Resolution (Xcode entry) | Launch Image name | Device |
|--------------------------|---------------------|------------------|
| 1x | Default-750.png | iPhone 6 |
| 2x | [email protected] | iPhone 4S |
| Retina 4 2x | [email protected] | iPhone 5, 5s, 5c |
| 3x | Default-1242.png | iPhone 6 Plus |
当然，在你完成这个之后你可以简单地使用[UIImage imageNamed:@"SplashImage"]
在Pichirichi的回答的帮助下，我实现了以下类别（iOS 7+）：UIImage+AssetLaunchImage
它实际上只是动态生成名称，但可能会有所帮助。
更新到最新的Swift语法（Swift 5）
func splashImageForOrientation(orientation: UIInterfaceOrientation) -> String? {
var viewSize = screenSize
var viewOrientation = "Portrait"
if orientation.isLandscape {
viewSize = CGSize(width: viewSize.height, height: viewSize.width)
viewOrientation = "Landscape"
}
if let infoDict = Bundle.main.infoDictionary, let launchImagesArray = infoDict["UILaunchImages"] as? [Any] {
for launchImage in launchImagesArray {
if let launchImage = launchImage as? [String: Any], let nameString = launchImage["UILaunchImageName"] as? String, let sizeString = launchImage["UILaunchImageSize"] as? String, let orientationString = launchImage["UILaunchImageOrientation"] as? String {
let imageSize = NSCoder.cgSize(for: sizeString)
if imageSize.equalTo(viewSize) && viewOrientation == orientationString {
return nameString
}
}
}
}
return nil
}
- (NSString *)splashImageNameForOrientation:(UIInterfaceOrientation)orientation {
CGSize viewSize = self.view.bounds.size;
NSString* viewOrientation = @"Portrait";
if (UIDeviceOrientationIsLandscape(orientation)) {
viewSize = CGSizeMake(viewSize.height, viewSize.width);
viewOrientation = @"Landscape";
}
NSArray* imagesDict = [[[NSBundle mainBundle] infoDictionary] valueForKey:@"UILaunchImages"];
for (NSDictionary* dict in imagesDict) {
CGSize imageSize = CGSizeFromString(dict[@"UILaunchImageSize"]);
if (CGSizeEqualToSize(imageSize, viewSize) && [viewOrientation isEqualToString:dict[@"UILaunchImageOrientation"]])
return dict[@"UILaunchImageName"];
}
return nil;
}
LaunchImages很特别，实际上并不是设备上的资产目录。如果您使用iFunBox / iExplorer / etc（或在模拟器上或在构建目录中），您可以看到最终名称，然后编写代码以使用它们 - 例如。对于仅限iOS7的iPhone项目，这将设置正确的启动图像：
NSString *launchImage;
if ((UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone) &&
([UIScreen mainScreen].bounds.size.height > 480.0f)) {
launchImage = @"LaunchImage-700-568h";
} else {
launchImage = @"LaunchImage-700";
}
[self.launchImageView setImage:[UIImage imageNamed:launchImage]];
我把它放到viewDidLoad中。
这不是很理想，如果Apple能给我们一个很好的API来做这件事会很棒。
我的应用程序目前仅支持iOS 7及更高版本。
这是我从资产目录中引用启动图像的方式：
NSDictionary *dict = @{@"320x480" : @"LaunchImage-700",
@"320x568" : @"LaunchImage-700-568h",
@"375x667" : @"LaunchImage-800-667h",
@"414x736" : @"LaunchImage-800-Portrait-736h"};
NSString *key = [NSString stringWithFormat:@"%dx%d",
(int)[UIScreen mainScreen].bounds.size.width,
(int)[UIScreen mainScreen].bounds.size.height];
UIImage *launchImage = [UIImage imageNamed:dict[key]];
如果要支持较旧的iOS版本，可以添加更多键值对。
这里是基于上面Cherpak Evgeny提供的解决方案的UIImage类别。
的UIImage + SplashImage.h：
#import <UIKit/UIKit.h>
/**
* Category on `UIImage` to access the splash image.
**/
@interface UIImage (SplashImage)
/**
* Return the name of the splash image for a given orientation.
* @param orientation The interface orientation.
* @return The name of the splash image.
**/
+ (NSString *)si_splashImageNameForOrientation:(UIInterfaceOrientation)orientation;
/**
* Returns the splash image for a given orientation.
* @param orientation The interface orientation.
* @return The splash image.
**/
+ (UIImage*)si_splashImageForOrientation:(UIInterfaceOrientation)orientation;
@end
的UIImage + SplashImage.m：
#import "UIImage+SplashImage.h"
@implementation UIImage (SplashImage)
+ (NSString *)si_splashImageNameForOrientation:(UIInterfaceOrientation)orientation
{
CGSize viewSize = [UIScreen mainScreen].bounds.size;
NSString *viewOrientation = @"Portrait";
if (UIDeviceOrientationIsLandscape(orientation))
{
viewSize = CGSizeMake(viewSize.height, viewSize.width);
viewOrientation = @"Landscape";
}
NSArray* imagesDict = [[[NSBundle mainBundle] infoDictionary] valueForKey:@"UILaunchImages"];
for (NSDictionary *dict in imagesDict)
{
CGSize imageSize = CGSizeFromString(dict[@"UILaunchImageSize"]);
if (CGSizeEqualToSize(imageSize, viewSize) && [viewOrientation isEqualToString:dict[@"UILaunchImageOrientation"]])
return dict[@"UILaunchImageName"];
}
return nil;
}
+ (UIImage*)si_splashImageForOrientation:(UIInterfaceOrientation)orientation
{
NSString *imageName = [self si_splashImageNameForOrientation:orientation];
UIImage *image = [UIImage imageNamed:imageName];
return image;
}
@end
@ codeman的答案更新为Swift 1.2：
func splashImageForOrientation(orientation: UIInterfaceOrientation, size: CGSize) -> String? {
var viewSize = size
var viewOrientation = "Portrait"
if UIInterfaceOrientationIsLandscape(orientation) {
viewSize = CGSizeMake(size.height, size.width)
viewOrientation = "Landscape"
}
if let imagesDict = NSBundle.mainBundle().infoDictionary as? [String: AnyObject] {
if let imagesArray = imagesDict["UILaunchImages"] as? [[String: String]] {
for dict in imagesArray {
if let sizeString = dict["UILaunchImageSize"], let imageOrientation = dict["UILaunchImageOrientation"] {
let imageSize = CGSizeFromString(sizeString)
if CGSizeEqualToSize(imageSize, viewSize) && viewOrientation == imageOrientation {
if let imageName = dict["UILaunchImageName"] {
return imageName
}
}
}
}
}
}
return nil
}
要调用它，并支持iOS 8的旋转：
override func viewWillAppear(animated: Bool) {
if let img = splashImageForOrientation(UIApplication.sharedApplication().statusBarOrientation, size: self.view.bounds.size) {
backgroundImage.image = UIImage(named: img)
}
}
override func viewWillTransitionToSize(size: CGSize, withTransitionCoordinator coordinator: UIViewControllerTransitionCoordinator) {
let orientation = size.height > size.width ? UIInterfaceOrientation.Portrait : UIInterfaceOrientation.LandscapeLeft
if let img = splashImageForOrientation(orientation, size: size) {
backgroundImage.image = UIImage(named: img)
}
}
正是我需要的，谢谢！
我刚刚写了一个通用方法来获取iPhone和iPad（横向，纵向）的启动图像名称，它对我有用，希望它也可以帮到你。我在其他SO答案的帮助下写了这个，感谢@Pichirichi的整个列表。
+(NSString*)getLaunchImageName
{
NSArray* images= @[@"LaunchImage.png", @"[email protected]",@"[email protected]",@"[email protected]",@"[email protected]",@"LaunchImage-700-Portrait@2x~ipad.png",@"LaunchImage-Portrait@2x~ipad.png",@"LaunchImage-700-Portrait~ipad.png",@"LaunchImage-Portrait~ipad.png",@"LaunchImage-Landscape@2x~ipad.png",@"LaunchImage-700-Landscape@2x~ipad.png",@"LaunchImage-Landscape~ipad.png",@"LaunchImage-700-Landscape~ipad.png"];
UIImage *splashImage;
if ([self isDeviceiPhone])
{
if ([self isDeviceiPhone4] && [self isDeviceRetina])
{
splashImage = [UIImage imageNamed:images[1]];
if (splashImage.size.width!=0)
return images[1];
else
return images[2];
}
else if ([self isDeviceiPhone5])
{
splashImage = [UIImage imageNamed:images[1]];
if (splashImage.size.width!=0)
return images[3];
else
return images[4];
}
else
return images[0]; //Non-retina iPhone
}
else if ([[UIDevice currentDevice] orientation]==UIDeviceOrientationPortrait || [[UIDevice currentDevice] orientation] == UIDeviceOrientationPortraitUpsideDown)//iPad Portrait
{
if ([self isDeviceRetina])
{
splashImage = [UIImage imageNamed:images[5]];
if (splashImage.size.width!=0)
return images[5];
else
return images[6];
}
else
{
splashImage = [UIImage imageNamed:images[7]];
if (splashImage.size.width!=0)
return images[7];
else
return images[8];
}
}
else
{
if ([self isDeviceRetina])
{
splashImage = [UIImage imageNamed:images[9]];
if (splashImage.size.width!=0)
return images[9];
else
return images[10];
}
else
{
splashImage = [UIImage imageNamed:images[11]];
if (splashImage.size.width!=0)
return images[11];
else
return images[12];
}
}
}
其他实用方法是
+(BOOL)isDeviceiPhone
{
if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone)
{
return TRUE;
}
return FALSE;
}
+(BOOL)isDeviceiPhone4
{
if ([[UIScreen mainScreen] bounds].size.height==480)
return TRUE;
return FALSE;
}
+(BOOL)isDeviceRetina
{
if ([[UIScreen mainScreen] respondsToSelector:@selector(displayLinkWithTarget:selector:)] &&
([UIScreen mainScreen].scale == 2.0)) // Retina display
{
return TRUE;
}
else // non-Retina display
{
return FALSE;
}
}
+(BOOL)isDeviceiPhone5
{
if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone && [[UIScreen mainScreen] bounds].size.height>480)
{
return TRUE;
}
return FALSE;
}
Swift版本的Cherpak Evgeny的答案：
func splashImageForOrientation(orientation: UIInterfaceOrientation) -> String {
var viewSize = self.view.bounds.size
var viewOrientation = "Portrait"
if UIInterfaceOrientationIsLandscape(orientation) {
viewSize = CGSizeMake(viewSize.height, viewSize.width)
viewOrientation = "Landscape"
}
let imagesDict = NSBundle.mainBundle().infoDictionary as Dictionary<NSObject,AnyObject>!
let imagesArray = imagesDict["UILaunchImages"] as NSArray
for dict in imagesArray {
let dictNSDict = dict as NSDictionary
let imageSize = CGSizeFromString(dictNSDict["UILaunchImageSize"] as String)
if CGSizeEqualToSize(imageSize, viewSize) && viewOrientation == (dictNSDict["UILaunchImageOrientation"] as String) {
return dictNSDict["UILaunchImageName"] as String
}
}
return ""
}
按照@ Pichirich的回答，我在Interface Builder中引用我的启动图像：
“LaunchImage.png”
...并且使用Xcode 5.0.2，它会自动从资产目录中直接提取相应的图像。
这就是我所期望的 - 除了苹果公司将“Default.png”重命名为“LaunchImage.png”的恶意恶作剧:)