我可以从委托对象调用ClassB方法吗?

如果objectA是objectB的委托,则当objectB从委托协议调用方法时:

if ([self.delegate resposndsToSelector:@selector(classBdidSomething:)]) {
    [self.delegate performSelector:@selector(classBdidSomething:) withObject:self];
}

#pragma mark -
#pragma mark Delegate methods
- (void)classBdidSomething:(ClassB *)objectB {
    [objectB methodToBeCalled];
}

如果在行上生成时出现错误/警告(如warning:no'-methodToBeCalled'method found):

[objectB methodToBeCalled];

这意味着您必须通过执行以下操作将ClassB导入到ClassA中:

#import "ClassB.h"