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動(dòng)態(tài)調(diào)用方法時(shí)會(huì)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];//獲得類(lèi)和方法的簽名
NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:methodSignature];
//從簽名獲得調(diào)用對(duì)象
[invocation setTarget:self];
//設(shè)置target
[invocation setSelector:selector];//設(shè)置selector
NSString *returnValue = nil;
NSString *argument1 = @"fist";
NSNumber *argument2 = [NSNumber numberWithInt:102];
[invocation setArgument:&argument1 atIndex:2];//設(shè)置參數(shù)，第一個(gè)參數(shù)index為2
[invocation setArgument:&argument2 atIndex:3];
[invocation retainArguments];//retain一遍參數(shù)
[invocation invoke];//調(diào)用
[invocation getReturnValue:&returnValue];//得到返回值，此時(shí)不會(huì)再調(diào)用，只是返回值
NSLog(@"return value = %@",returnValue);
} 另外一個(gè)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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