要测试 object 是否是类 a 的实例：

[yourObject isKindOfClass:[a class]]
// Returns a Boolean value that indicates whether the receiver is an instance of 
// given class or an instance of any class that inherits from that class.

或者

[yourObject isMemberOfClass:[a class]]
// Returns a Boolean value that indicates whether the receiver is an instance of a 
// given class.

要获取对象的类名，您可以使用NSStringFromClass函数：

NSString *className = NSStringFromClass([yourObject class]);

或来自objective-c运行时api的c函数：

#import <objc/runtime.h>

/* ... */

const char* className = class_getName([yourObject class]);
NSLog(@"yourObject is a: %s", className);

编辑： 在斯威夫特

if touch.view is UIPickerView {
    // touch.view is of type UIPickerView
}