NSInvocationを使用してクラスメソッドを呼び出すにはどうすればよいですか？

Question

NSMethodSignatureは+ (NSMethodSignature *)instanceMethodSignatureForSelector:(SEL)aSelectorのNSObjectとなります。次に、NSInvocationを+ (NSInvocation *)invocationWithMethodSignature:(NSMethodSignature *)signature

で作成してください。 のメソッドシグネチャしか取得できません。クラスメソッドはどうですか？

NSMethodSignature *pMS = [[YourObject class] methodSignatureForSelector: (SEL)aSelector]; 

あなたは、クラスのメソッドを取得するために使用できるクラスオブジェクト（シングルトン）のインスタンスを返す[YourObject class]フラグメント：

Answer 1

次の方法でクラスメソッドを取得することができます。

追加：新しいコメントは下記の通りです。あなたは、次の操作を行うことができます

NSMethodSignature *pMS = [YourObject methodSignatureForSelector: (SEL)aSelector]; 

Answer 2

ここmethodForSignature:とinstanceMethodForSignature:

@interface SomeObject : NSObject 
+ (void)instanceAndClass; 
- (void)instanceAndClass; 
+ (void)classOnly; 
- (void)instanceOnly; 
@end 

@implementation SomeObject 
+ (void)instanceAndClass { NSLog(@"Class version"); } 
- (void)instanceAndClass { NSLog(@"Instance version"); }  
+ (void)classOnly { NSLog(@"Class only"); } 
- (void)instanceOnly { NSLog(@"Instance only"); } 
@end 

@implementation Foo 

- (void)invoke:(id)receiver signature:(NSMethodSignature *)signature selector:(SEL)selector { 
    if (!signature) { 
     NSLog(@"method signature is nil"); 
     return; 
    }   
    NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:signature]; 
    invocation.selector = selector; 
    invocation.target = receiver; 
    [invocation invoke]; 
} 

- (void)foo { 
    NSMethodSignature *signature; 
    SomeObject *someObject = [SomeObject new]; 

    signature = [someObject methodSignatureForSelector:@selector(instanceAndClass)]; 
    [self invoke:someObject signature:signature selector:@selector(instanceAndClass)]; 
    // 2015-07-10 11:01:10.227 FooBar[65312:3097866] Instance version 
    [self invoke:[someObject class] signature:signature selector:@selector(instanceAndClass)]; 
    // 2015-07-10 11:01:10.227 FooBar[65312:3097866] Class version 

    signature = [someObject methodSignatureForSelector:@selector(classOnly)]; 
    [self invoke:someObject signature:signature selector:@selector(classOnly)]; 
    // 2015-07-10 11:01:10.227 FooBar[65312:3097866] method signature is nil 

    signature = [[someObject class] methodSignatureForSelector:@selector(classOnly)]; 
    [self invoke:[someObject class] signature:signature selector:@selector(classOnly)]; 
    // 2015-07-10 11:01:10.228 FooBar[65312:3097866] Class only 

    signature = [someObject methodSignatureForSelector:@selector(instanceOnly)]; 
    [self invoke:someObject signature:signature selector:@selector(instanceOnly)]; 
    // 2015-07-10 11:01:10.228 FooBar[65312:3097866] Instance only 

    signature = [[someObject class] methodSignatureForSelector:@selector(instanceOnly)]; 
    [self invoke:[someObject class] signature:signature selector:@selector(instanceOnly)]; 
    2015-07-10 11:01:10.228 FooBar[65312:3097866] method signature is nil 

    signature = [[someObject class] instanceMethodSignatureForSelector:@selector(instanceOnly)]; 
    [self invoke:someObject signature:signature selector:@selector(instanceOnly)]; 
    // 2015-07-10 11:01:10.228 FooBar[65312:3097866] Instance only 
}