[1]在Iphone项目中,大家会看到一个默认的Autorelease pool,程序开始时创建,程序退出时销毁,按照对Autorelease的理解,岂不是所有autorelease pool里的对象在程序退出时才release, 这样跟内存泄露有什么区别?
答案是,对于每一个Runloop, 系统会隐式创建一个Autorelease pool,这样所有的release pool会构成一个象CallStack一样的一个栈式结构,在每一个Runloop结束时,当前栈顶的Autorelease pool会被销毁,这样这个pool里的每个Object会被release。
NSString* globalObject;
- (void)applicationDidFinishLaunching:(UIApplication *)application
{
globalObject = [[NSString alloc] initWithFormat:@"Test"];
NSLog(@"Retain count after create: %d", [globalObject retainCount]); // output 1.
[globalObject retain];
NSLog(@"Retain count after retain: %d", [globalObject retainCount]); // output 2.
}
- (void)applicationWillTerminate:(UIApplication *)application
{
NSLog(@"Retain count after Button click runloop finished: %d", [globalObject retainCount]);
// 输出1. Button click loop finished, it's autorelease pool released, globalObject get released once.
}
-(IBAction)onButtonClicked
{
[globalObject autorelease];
NSLog(@"Retain count after autorelease: %d", [globalObject retainCount]);
// 输出2。 Autorelease被call, globalObject被加如当前的AutoreleaePool。
}