YYClassMethodInfo.h.m

/**
 Method information.
 */
@interface YYClassMethodInfo : NSObject
@property (nonatomic, assign, readonly) Method method;                  ///< method opaque struct
@property (nonatomic, strong, readonly) NSString *name;                 ///< method name
@property (nonatomic, assign, readonly) SEL sel;                        ///< method's selector
@property (nonatomic, assign, readonly) IMP imp;                        ///< method's implementation
@property (nonatomic, strong, readonly) NSString *typeEncoding;         ///< method's parameter and return types
@property (nonatomic, strong, readonly) NSString *returnTypeEncoding;   ///< return value's type
@property (nullable, nonatomic, strong, readonly) NSArray<NSString *> *argumentTypeEncodings; ///< array of arguments' type

/**
 Creates and returns a method info object.
 创建和返回一个方法信息模型对象
 
 @param method method opaque struct
 @return A new object, or nil if an error occurs.
 */
- (instancetype)initWithMethod:(Method)method;
@end

@implementation YYClassMethodInfo

- (instancetype)initWithMethod:(Method)method {

    // 方法结构体为 nil ， 直接返回 nil
    if (!method) return nil;

    // 初始化对象
    self = [super init];

    // 记录传入的方法
    _method = method;

    // 获取方法的声明
    _sel = method_getName(method);

    // 获取方法的实现
    _imp = method_getImplementation(method);

    // 获取方法的名称
    const char *name = sel_getName(_sel);
    if (name) {
        _name = [NSString stringWithUTF8String:name];
    }


    // 参数和返回值
    const char *typeEncoding = method_getTypeEncoding(method);
    if (typeEncoding) {
        _typeEncoding = [NSString stringWithUTF8String:typeEncoding];
    }

    // 返回值的类型
    char *returnType = method_copyReturnType(method);
    if (returnType) {
        _returnTypeEncoding = [NSString stringWithUTF8String:returnType];
        free(returnType);
    }

    // 获取参数的个数 去获取参数的类型
    unsigned int argumentCount = method_getNumberOfArguments(method);
    if (argumentCount > 0) {
        NSMutableArray *argumentTypes = [NSMutableArray new];
        for (unsigned int i = 0; i < argumentCount; i++) {
            char *argumentType = method_copyArgumentType(method, i);
            NSString *type = argumentType ? [NSString stringWithUTF8String:argumentType] : nil;
            [argumentTypes addObject:type ? type : @""];
            if (argumentType) free(argumentType);
        }
        _argumentTypeEncodings = argumentTypes;
    }
    return self;
}

@end