环境变量、block、修饰符：block对环境变量的引用和修改需要通过修饰符来限定

环境变量、block、修饰符：block对环境变量的引用和修改需要通过修饰符来限定。

http://www.cnblogs.com/fengmin/p/5816580.html

- (NSUInteger)getSize {

__block NSUInteger size = 0;

dispatch_sync(self.ioQueue, ^{

NSDirectoryEnumerator *fileEnumerator = [_fileManager enumeratorAtPath:self.diskCachePath];

for (NSString *fileName in fileEnumerator) {

NSString *filePath = [self.diskCachePath stringByAppendingPathComponent:fileName];

NSDictionary *attrs = [[NSFileManager defaultManager] attributesOfItemAtPath:filePath error:nil];

size += [attrs fileSize];

}

});

return size;

}