直接上代码
main.h
#import <Foundation/Foundation.h> #import "MyClass.h" int main (int argc, const char * argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; MyClass *myClass = [[MyClass alloc] init]; NSString *myString = @"My string"; //普通调用 NSString *normalInvokeString = [myClass appendMyString:myString]; NSLog(@"The normal invoke string is: %@", normalInvokeString); //NSInvocation调用 SEL mySelector = @selector(appendMyString:); NSMethodSignature * sig = [[myClass class] instanceMethodSignatureForSelector: mySelector]; NSInvocation * myInvocation = [NSInvocation invocationWithMethodSignature: sig]; [myInvocation setTarget: myClass]; [myInvocation setSelector: mySelector]; [myInvocation setArgument: &myString atIndex: 2]; NSString * result = nil; [myInvocation retainArguments]; [myInvocation invoke]; [myInvocation getReturnValue: &result]; NSLog(@"The NSInvocation invoke string is: %@", result); [myClass release]; [pool drain]; return 0; }
MyClass.h
#import <Foundation/Foundation.h> @interface MyClass : NSObject { } - (NSString *)appendMyString:(NSString *)string; @end
MyClass.m
#import "MyClass.h" @implementation MyClass - (id)init { self = [super init]; if (self) { // Initialization code here. } return self; } - (NSString *)appendMyString:(NSString *)string { NSString *mString = [NSString stringWithFormat:@"%@ after append method", string]; return mString; } - (void)dealloc { [super dealloc]; } @end
这里说明一下[myInvocation setArgument: &myString atIndex: 2];为什么index从2开始
文档中的说明
Indices 0 and 1 indicate the hidden arguments self and _cmd, respectively; you should set these values directly with the setTarget: and setSelector: methods. Use indices 2 and greater for the arguments normally passed in a message.意思就是0和1是隐藏参数,而这两个参数是要在setTarget和setSelector设置的,所以我们调用方法中的参数就要从2开始了,如果有多个参数,那么就依次递增,ok,就写这么多