iOS 模态视图跳转 背景透明

ModalViewController * modal = [[ModalViewController alloc] init];

//把当前控制器作为背景

self.definesPresentationContext =YES;

//设置模态视图弹出样式

modal.modalPresentationStyle =UIModalPresentationOverFullScreen; 

 [selfpresentViewController:modal animated:YEScompletion:nil];