转自:https://stackoverflow.com/questions/918698/why-are-objective-c-delegates-usually-given-the-property-assign-instead-of-retai转自:https://stackoverflow.com/questions/918698/w
转自:https://stackoverflow.com/questions/918698/why-are-objective-c-delegates-usually-given-the-property-assign-instead-of-retai转自:https://stackoverflow.com/questions/918698/w