动态调用方法时会用到,例子
-(NSString *)myMethod:(NSString *)param1 withParam2:(NSNumber *)param2 { NSString *result = @"objc"; NSLog(@"par = %@",param1); NSLog(@"par 2 = %@",param2); return result; }
-(void)invokeMyMethodDynamically { SEL selector = @selector(myMethod:withParam2:); NSMethodSignature *methodSignature = [[self class] instanceMethodSignatureForSelector:selector];//获得类和方法的签名 NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:methodSignature]; //从签名获得调用对象 [invocation setTarget:self]; //设置target [invocation setSelector:selector];//设置selector NSString *returnValue = nil; NSString *argument1 = @"fist"; NSNumber *argument2 = [NSNumber numberWithInt:102]; [invocation setArgument:&argument1 atIndex:2];//设置参数,第一个参数index为2 [invocation setArgument:&argument2 atIndex:3]; [invocation retainArguments];//retain一遍参数 [invocation invoke];//调用 [invocation getReturnValue:&returnValue];//得到返回值,此时不会再调用,只是返回值 NSLog(@"return value = %@",returnValue); } 另外一个例子: SEL selector = @selector(myMethod:setValue2:);
NSMethodSignature *signature = [MyObject instanceMethodSignatureF orSelector:selector]; NSInvocation *invocation = [NSInvocation invocationWithMethodSign ature:signature]; [invocation setSelector:selector];
NSString *str1 = @"someString"; NSString *str2 = @"someOtherString";
//The invocation object must retain its arguments [str1 retain]; [str2 retain];
//Set the arguments [invocation setTarget:targetInstance]; [invocation setArgument:&str1 atIndex:2]; [invocation setArgument:&str2 atIndex:3];
[NSTimer scheduledTimerWithTimeIn terval:0.1 invocation:invocation repeats:YES]
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