小编Ste*_*azy的帖子

我正在通过这种方法替换@synthesized(自我)锁

void _ThreadsafeInit(Class theClassToInit, void *volatile *theVariableItLivesIn, void(^InitBlock)(void))
{
    //this is what super does :X
    struct objc_super mySuper = {
        .receiver = (id)theClassToInit,
        .super_class = class_getSuperclass(theClassToInit)
    };

id (*objc_superAllocTyped)(struct objc_super *, SEL, NSZone *) = (void *)&objc_msgSendSuper;
//    id (*objc_superAllocTyped)(id objc_super, SEL, NSZone *) = (void *)&objc_msgSend;

    do {
        id temp = [(*objc_superAllocTyped)(&mySuper /*theClassToInit*/, @selector(allocWithZone:), NULL) init];//get superclass in case alloc is blocked in this class;
        if(OSAtomicCompareAndSwapPtrBarrier(0x0, temp, theVariableItLivesIn)) { //atomic operation forces synchronization
            if( InitBlock != NULL ) { …