Day8 oc weak syntax

oc weak syntax

The method call of oc is to detect whether the object has implemented the corresponding method at runtime

#import <Foundation/Foundation.h>

//@interface Person:NSObject
//@end

//Added here: NSObject

@implementation Person:NSObject
- (void)test
{
     NSLog(@"test");
}
@end

intmain()
{
     Person *p=[Person new];
     [p test];
     return 0;
}

 If the test method implementation is commented out, compiling and linking will not report an error; if the test method is only declared and not defined, compiling and linking will not report an error; only an error will be reported at runtime; if test is defined but not declared, compile and link and run No error will be reported, but this is not recommended; if Person does not declare it, no error will be reported as above, but this is not recommended.