如何在没有编译css in react的情况下观看sass文件夹的更改(How to watch sass folder for changes without compiling in css in react)

 
 
 这真的有必要吗？ 
 
 
 如果您仍在使用手动内存管理。 如果没有保留， returnObject从数组中删除它就可以释放returnObject 。 可变数组保留它包含的对象，并在删除时释放它们。 在移除对象之前保留对象可防止对象被释放; 自动释放它允许对象保持足够长的时间以使调用方法接收它。 
 
 如果您正在使用ARC（并且没有太多理由不这样做），您不必担心任何问题。 编译器将确定何时保留以及何时为您释放。 
 
 
 
 我的印象是运行时将在运行循环迭代结束时通过removeLastObject销毁从内容中删除的对象 
 
 
 如果NSMutableArray在移除对象时自动释放对象会发生这种情况，但我认为没有任何理由认为它确实存在。 如果-removeLastObject返回已删除的对象，则可以指望已删除的对象被自动释放，但它不会。 你永远不应该假设另一个对象对它拥有的对象做了什么。 

 
 
Is this really necessary?
 
 
It is if you're still using manual memory management. Without that retain, returnObject could be deallocated as soon as you remove it from the array. A mutable array retains the objects that it contains and releases them upon removal. Retaining an object before removing it prevents the object from being deallocated; autoreleasing it allows the object to stick around long enough for the calling method to receive it.
 
If you're using ARC (and there aren't many reasons not to), you don't have to worry about any of that. The compiler will figure out when to retain and when to release for you.
 
 
 
I'm under the impression that the runtime will destroy the object removed from contents via removeLastObject at the end of a run-loop iteration
 
 
That's what would happen if NSMutableArray autoreleased objects when it removes them, but I don't see any reason to think that it does. You could count on the removed object being autoreleased if -removeLastObject returned the removed object, but it doesn't. You should never make assumptions about what another object does with the objects it owns.