iOS7 came, new guideline for app icons and launch image

image and icon size only for iOS7

https://developer.apple.com/library/ios/documentation/userexperience/conceptual/mobilehig/IconMatrix.html#//apple_ref/doc/uid/TP40006556-CH27-SW1

app icons

https://developer.apple.com/library/ios/documentation/userexperience/conceptual/mobilehig/AppIcons.html#//apple_ref/doc/uid/TP40006556-CH19-SW1

Launch images

https://developer.apple.com/library/ios/documentation/userexperience/conceptual/mobilehig/LaunchImages.html#//apple_ref/doc/uid/TP40006556-CH22-SW1

注意：如果使用xcode5，app icons and launch images file name並不需要特定。

"image and icon size only for iOS7"文章裏面有個表格說明了：如果你的app只是only for iOS7，要support both iphone (only retina, iOS 7不支持非高清的iphone) and ipad (retina or non-retina)，那麼

下列size的icon是required的

120*120

76*76

152*152

1024*1024 (for submission to app store)

下列size icon是recommend的

40*40

80*80

29*29

58*58

下列size launch image是required的

640*960

640*1136

768*1024 (portrait)

1536*2048 (portrait, retina)

1024*768 (landscape)

2048*1536 (landscape, retina)

注意：guideline提到：for iOS7, Launch images for all devices must include the status bar region, （待測試）是否在ios6下不需要使用不帶status bar高度的launch image

refer link: 

https://developer.apple.com/library/ios/qa/qa1686/_index.html

http://stackoverflow.com/questions/18523193/ios-app-submission-invalid-image-sizes

http://blog.manbolo.com/2013/08/15/new-metrics-for-ios-7-app-icons

如果你的app還要支持iOS 5 and 6, for both iphone(retina or non) and ipad (retina or non)，那麼下面size的icon是required (待檢測）

512*512 (for submission to app store)

57*57

recommended:

114*114

72*72

144*144

50*50

100*100

下列size launch image是required的

320*480

guideline提到：For all images and icons, the PNG format is recommended，其他格式的image(e.g. jpg)還沒搞清楚在xcode5裏如果被添加爲icon。下面這條link有apple review feedback:Invalid Image - For iOS applications, icons included in the binary submission must be in the PNG format.

http://stackoverflow.com/questions/18523193/ios-app-submission-invalid-image-sizes

下面link講解了如何在xcode5的asset catalog裏使用jpg format的image

http://stackoverflow.com/questions/18785946/how-can-i-add-jpegs-to-an-asset-catalog-in-xcode

http://stackoverflow.com/questions/19032855/assets-catalog-imageset-edit-contents-json

other links:

http://stackoverflow.com/questions/18624587/how-do-you-update-the-app-icons-and-launch-images-to-support-ios-6-and-7-simulta

http://stackoverflow.com/questions/18999842/sizes-and-names-on-icons-and-launch-images-in-xcode-5-ios-7

該link還提供了一個網站用來生成icons http://makeappicon.com/

http://mrgan.tumblr.com/post/708404794/ios-app-icon-sizes

http://ivomynttinen.com/blog/the-ios-7-design-cheat-sheet/