示例代码:
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// - weak & strong
#define myWeakify(VAR) \
try {} @finally {} \
__weak __typeof__(VAR) VAR##_myWeak_ = (VAR)
#define myStrongify(VAR) \
try {} @finally {} \
__strong __typeof__(VAR) VAR = VAR##_myWeak_
#define myStrongifyRetVIfNil(VAR, RET) \
try {} @finally {} \
__strong __typeof__(VAR) VAR = VAR##_myWeak_;\
if (VAR == nil) return RET
#define myStrongifyRetNIfNil(VAR) \
try {} @finally {} \
__strong __typeof__(VAR) VAR = VAR##_myWeak_;\
if (VAR == nil) return
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使用如下:
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- ( void )handleFromVC
{
NSArray *viewControllers = self.navigationController.viewControllers;
@myWeakify(self);
[viewControllers enumerateObjectsWithOptions:NSEnumerationReverse usingBlock:^(id _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
@myStrongifyRetNIfNil(self);
//代码
}];
}
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原文链接:http://blog.csdn.net/robinson_911/article/details/73471384