performSelector is hidden from swift,can't compile if use performSelector in swift. But performSelector is valid in objective-c. With objc bridge,we can use performSelector now.
XPerformSelector.perform(self, selector: "test")
Swift and Objective-C in the Same Project
+(void) perform: (id)target selector:(SEL)selector;
+(void) perform: (id)target selector:(SEL)selector count:(int)count, ...;
+(void) perform: (id)target selector:(SEL)selector withObject:(id)arg1;
+(void) perform: (id)target selector:(SEL)selector withObject:(id)arg1 withObject:(id)arg2;
+(void) perform: (id)target selector:(SEL)selector afterDelay:(NSTimeInterval)delay;
+(void) perform: (id)target selector:(SEL)selector withObject:(id)arg1 afterDelay:(NSTimeInterval)delay;