instancesRespondToSelector與respondsToSelector的區別

Test1.h

@interface Test1 : NSObject

- (void)objectFun;

+ (void)classFun;

@end

 

Test1.m

@implementation Test1

- (void)objectFun
{
    NSLog(@"object function");
}

+ (void)classFun
{
    NSLog(@"class function");
}

@end

 

測試類：

BOOL flag;

flag = [Test1 instancesRespondToSelector:@selector(objectFun)]; //YES

flag = [Test1 instancesRespondToSelector:@selector(classFun)]; //NO

flag = [Test1 respondsToSelector:@selector(objectFun)]; //NO

flag = [Test1 respondsToSelector:@selector(classFun)]; //YES

Test1 *obj = [[Test1 alloc] init];

flag = [obj respondsToSelector:@selector(objectFun)]; //YES

flag = [obj respondsToSelector:@selector(classFun)]; //NO

 

總結：

1. instancesRespondToSelector只能寫在類名后面，respondsToSelector可以寫在類名和實例名后面。

2. [類 instancesRespondToSelector]判斷的是該類的實例是否包含某方法，等效於：[該類的實例 respondsToSelector]。

3. [類 respondsToSelector]用於判斷是否包含某個類方法。