再次理解ARC引用计数

ARC代码：

NSObject *p = [NSObject new];

编译完的MRC代码：

NSObject *temp = [NSObject new];

p = [temp retain];

[temp release];

ARC代码:

__weak NSObject *p = [NSObject new];

编译完的MRC代码：

NSObject *temp = [NSObject new];

p = temp;

[temp release];