PerformSelector参数扩展
在iOS开发中，我们可以使用使用performSelector来调用方法，但是受限与以下方法，我们想要传递参数的话也就只能传递一个两个或者不传。
- (id)performSelector:(SEL)aSelector; - (id)performSelector:(SEL)aSelector withObject:(id)object; - (id)performSelector:(SEL)aSelector withObject:(id)object1 withObject:(id)object2; - (void)performSelectorOnMainThread:(SEL)aSelector withObject:(nullable id)arg waitUntilDone:(BOOL)wait modes:(nullable NSArray<NSString *> *)array; - (void)performSelectorOnMainThread:(SEL)aSelector withObject:(nullable id)arg waitUntilDone:(BOOL)wait; // equivalent to the first method with kCFRunLoopCommonModes - (void)performSelector:(SEL)aSelector onThread:(NSThread *)thr withObject:(nullable id)arg waitUntilDone:(BOOL)wait modes:(nullable NSArray<NSString *> *)array API_AVAILABLE(macos(10.5), ios(2.0), watchos(2.0), tvos(9.0)); - (void)performSelector:(SEL)aSelector onThread:(NSThread *)thr withObject:(nullable id)arg waitUntilDone:(BOOL)wait API_AVAILABLE(macos(10.5), ios(2.0), watchos(2.0), tvos(9.0)); // equivalent to the first method with kCFRunLoopCommonModes - (void)performSelectorInBackground:(SEL)aSelector withObject:(nullable id)arg API_AVAILABLE(macos(10.5), ios(2.0), watchos(2.0), tvos(9.0)); 所以为了实现多个参数的传递，我们可以使用以下方法：
// 下面的例子都是基于这个方法 - (void)testFirst:(NSString *)argA second:(NSString *)argB third:(NSString *)argC { NSLog(@"当前线程:%@", [NSThread currentThread]); NSLog(@"first:%@ - second:%@ - third:%@", argA, argB, argC); } -
- 将方法的多个参数包装成一个参数(如NSDictionary)
略
-
- 使用
NSInvocation
- 使用
// 1. 获取方法签名 NSMethodSignature *sign = [self methodSignatureForSelector:aSelector]; // 2. 获取参数个数 NSUInteger number = sign.numberOfArguments; NSInteger count = MIN(args.count, number - 2); // 3. 利用NSInvocation对象对方法进行包装 NSInvocation *invo = [NSInvocation invocationWithMethodSignature:sign]; // 3.1 设置方法调用者 [invo setTarget:self]; // 3.2 设置方法名 [invo setSelector:aSelector]; // 3.3 设置方法参数 for (NSInteger i = 0; i < count; i ++) { id arg = args[i]; [invo setArgument:&arg atIndex:i + 2]; } // 4. 方法调用 [invo invoke]; 此处，我是创建了一个NSObject的Category,暴露一下方法给调用者
- (void)ps_performSelector:(SEL)aSelector onThread:(NSThread *)thr waitUntilDone:(BOOL)wait withObjects:(id)arg, ... NS_REQUIRES_NIL_TERMINATION; - (id)ps_performSelector:(SEL)aSelector withObjects:(id)arg, ... NS_REQUIRES_NIL_TERMINATION; 具体使用如下：
[self ps_performSelector:@selector(testFirst:second:third:) withObjects:@"AA", @"BB", @"CC", nil]; [self ps_performSelector:@selector(testFirst:second:third:) withObjects:@"E", @"F", nil]; [self ps_performSelector:@selector(testFirst:second:third:) onThread:[NSThread mainThread] waitUntilDone:NO withObjects:@"A", @"B", @"C", nil]; // 输出结果如下 /** 当前线程:<NSThread: 0x60000007d500>{number = 1, name = main} first:AA - second:BB - third:CC 当前线程:<NSThread: 0x60000007d500>{number = 1, name = main} first:E - second:F - third:(null) 当前线程:<NSThread: 0x60000007d500>{number = 1, name = main} first:A - second:B - third:C */ performSelector在最后也是使用objc_msgSend进行消息转发，这里也可以直接使用objc_msgSend进行转发
// 需要先引入#import <objc/message.h> SEL sel = @selector(testFirst:second:third:); ((void (*) (id, SEL, NSString *, NSString *, NSString *)) objc_msgSend) (self, sel, @"AA", @"BB", @"CC");