摘要：There are issues in iPhone OS 2.x where the imageNamed: cache would not be cleared, even after a memory warning. At the same time +imageNamed: has gotten a lot of use not for the cache, but for the convenience, which has probably magnified the problem more than it should have been.On the speed front 阅读全文

摘要：比如 ARC 状态时候， retain release 等消息发送是不能使用的。看宏定义：没限定：- (BOOL)conformsToProtocol:(Protocol *)aProtocol;- (BOOL)respondsToSelector:(SEL)aSelector;有限定：- (id)retain NS_AUTOMATED_REFCOUNT_UNAVAILABLE;- (oneway void)release NS_AUTOMATED_REFCOUNT_UNAVAILABLE;- (id)autorelease NS_AUTOMATED_REFCOUNT_UNAVAILABLE; 阅读全文

摘要：Using the correct data types for your variables helps to maximize the performance and portability of your programs. Data alignment specifies how data is laid out in memory. A data type’snatural alignmentspecifies the default alignment of values of that that type.Table 1lists the ANSI C scalar data t 阅读全文

摘要：先贴些， 周末有空儿整理...didReceiveMemoryWarningpracticesAs you said, the controller's default implementation ofdidReceiveMemoryWarningreleases its view if it is 'safe to do so'. While it's not clear from Apple's documents what 'safe to do so' means, it is generally recognized as i 阅读全文