iPhone开发学习笔记一(Default,Icon.png/SandBox/MemoryLimit)

1)Default.png, Icon.png:

    Apple recommends matching Default.png to your application’s background. Many developers use Default.png launch images for a logo splash or for a “Please wait” message. These go against Apple’s human interface guidelines (launch images should provide visual continuity, not advertising or excuses for delays) but are perfectly understandable uses.

    The “official” application icon size is 57-by-57 pixels. SpringBoard automatically scales larger art. Provide flat (not glossy) art with squared corners. SpringBoard smoothes and rounds those corners and adds an automatic gloss and shine effect. If for some com- pelling reason you need to use prerendered art, set UIPrerenderedIcon to <true/> in your Info.plist file.

    If you plan to submit your application to App Store, you need to create a high-resolution (512-by-512 pixel) version of your icon. Although you can up sample your 57-by-57 icon.png art, it won’t look good. Going the other way allows you to maintain high-quality art that you can compress to your icon as needed.

 

2)SandBox:

    Your application owns its own Library, Documents, and /tmp folders.These mimic the standard folders you’d use on a less-restrictive platform but specifically limits your ability to write and access this data.

    Note:Sandbox specification files (using the .sb extension) are stored in /var/mobile/Applications along with the actual sandbox folders. These files control privileges such as read-and-write access to various bits of the file system. If such a possibility should present itself, do not edit this file directly. You will render your application unusable. An exemplar sandbox file usually appears in /usr/share/sandbox.

    /var/mobile/Applications:

 

3) MEMORY LIMIS about "Why choose PNG-formed images in iPhone apps development?":
    Xcode automatically optimizes your PNG images using the pngcrush utility shipped with the SDK. (You’ll find the program in the iPhoneOS platform folders in /Developer. Run it from the command line with the –iphone switch to convert standard PNG files to iPhone- formatted ones.) For this reason, use PNG images in your iPhone apps where possible as your preferred image format.