问题
I'm upgrading an app to iOS 7 and am running into a problem where all buttons turn to grey after I display a modal view. They're still clickable though. It only happens with modal views and not popovers.
回答1:
As @CarmeloS points out the tint color is most likely your problem. Look at UIAppearance and or another view/viewcontroller higher up in the view heirachy as I believe this is now an inherited trait. So you may have set it it elsewhere.
回答2:
Maybe it's the tintColor attribute, try setting UIView.tintColor Attribute explicitly.
回答3:
Try to use tintAdjustmentMode = UIViewTintAdjustmentModeNormal for elements with tint color.
来源：https://stackoverflow.com/questions/19244991/ios-7-modal-view-makes-buttons-grey-disabled