Пост от e.James дал отличное решение для большинства просмотров. Но для зависимых от клавиатуры представлений, таких как UITextField и UITextView, это часто приводит к ситуации бесконечного цикла. Чтобы избавиться от него, я исправил его с помощью дополнительного кода, который проверяет, содержится ли селектор в конкретном протоколе (ах).
WZProtocolInterceptor.h
#import <Foundation/Foundation.h>
@interface WZProtocolInterceptor : NSObject
@property (nonatomic, readonly, copy) NSArray * interceptedProtocols;
@property (nonatomic, weak) id receiver;
@property (nonatomic, weak) id middleMan;
- (instancetype)initWithInterceptedProtocol:(Protocol *)interceptedProtocol;
- (instancetype)initWithInterceptedProtocols:(Protocol *)firstInterceptedProtocol, ... NS_REQUIRES_NIL_TERMINATION;
- (instancetype)initWithArrayOfInterceptedProtocols:(NSArray *)arrayOfInterceptedProtocols;
@end
WZProtocolInterceptor.m
#import <objc/runtime.h>
#import "WZProtocolInterceptor.h"
static inline BOOL selector_belongsToProtocol(SEL selector, Protocol * protocol);
@implementation WZProtocolInterceptor
- (id)forwardingTargetForSelector:(SEL)aSelector
{
if ([self.middleMan respondsToSelector:aSelector] &&
[self isSelectorContainedInInterceptedProtocols:aSelector])
return self.middleMan;
if ([self.receiver respondsToSelector:aSelector])
return self.receiver;
return [super forwardingTargetForSelector:aSelector];
}
- (BOOL)respondsToSelector:(SEL)aSelector
{
if ([self.middleMan respondsToSelector:aSelector] &&
[self isSelectorContainedInInterceptedProtocols:aSelector])
return YES;
if ([self.receiver respondsToSelector:aSelector])
return YES;
return [super respondsToSelector:aSelector];
}
- (instancetype)initWithInterceptedProtocol:(Protocol *)interceptedProtocol
{
self = [super init];
if (self) {
_interceptedProtocols = @[interceptedProtocol];
}
return self;
}
- (instancetype)initWithInterceptedProtocols:(Protocol *)firstInterceptedProtocol, ...;
{
self = [super init];
if (self) {
NSMutableArray * mutableProtocols = [NSMutableArray array];
Protocol * eachInterceptedProtocol;
va_list argumentList;
if (firstInterceptedProtocol)
{
[mutableProtocols addObject:firstInterceptedProtocol];
va_start(argumentList, firstInterceptedProtocol);
while ((eachInterceptedProtocol = va_arg(argumentList, id))) {
[mutableProtocols addObject:eachInterceptedProtocol];
}
va_end(argumentList);
}
_interceptedProtocols = [mutableProtocols copy];
}
return self;
}
- (instancetype)initWithArrayOfInterceptedProtocols:(NSArray *)arrayOfInterceptedProtocols
{
self = [super init];
if (self) {
_interceptedProtocols = [arrayOfInterceptedProtocols copy];
}
return self;
}
- (void)dealloc
{
_interceptedProtocols = nil;
}
- (BOOL)isSelectorContainedInInterceptedProtocols:(SEL)aSelector
{
__block BOOL isSelectorContainedInInterceptedProtocols = NO;
[self.interceptedProtocols enumerateObjectsUsingBlock:^(Protocol * protocol, NSUInteger idx, BOOL *stop) {
isSelectorContainedInInterceptedProtocols = selector_belongsToProtocol(aSelector, protocol);
* stop = isSelectorContainedInInterceptedProtocols;
}];
return isSelectorContainedInInterceptedProtocols;
}
@end
BOOL selector_belongsToProtocol(SEL selector, Protocol * protocol)
{
// Reference: https://gist.github.com/numist/3838169
for (int optionbits = 0; optionbits < (1 << 2); optionbits++) {
BOOL required = optionbits & 1;
BOOL instance = !(optionbits & (1 << 1));
struct objc_method_description hasMethod = protocol_getMethodDescription(protocol, selector, required, instance);
if (hasMethod.name || hasMethod.types) {
return YES;
}
}
return NO;
}
А вот версия Swift 2:
//
// NSProtocolInterpreter.swift
// Nest
//
// Created by Manfred Lau on 11/28/14.
// Copyright (c) 2014 WeZZard. All rights reserved.
//
import Foundation
/**
`NSProtocolInterceptor` is a proxy which intercepts messages to the middle man
which originally intended to send to the receiver.
- Discussion: `NSProtocolInterceptor` is a class cluster which dynamically
subclasses itself to conform to the intercepted protocols at the runtime.
*/
public final class NSProtocolInterceptor: NSObject {
/// Returns the intercepted protocols
public var interceptedProtocols: [Protocol] { return _interceptedProtocols }
private var _interceptedProtocols: [Protocol] = []
/// The receiver receives messages
public weak var receiver: NSObjectProtocol?
/// The middle man intercepts messages
public weak var middleMan: NSObjectProtocol?
private func doesSelectorBelongToAnyInterceptedProtocol(
aSelector: Selector) -> Bool
{
for aProtocol in _interceptedProtocols
where sel_belongsToProtocol(aSelector, aProtocol)
{
return true
}
return false
}
/// Returns the object to which unrecognized messages should first be
/// directed.
public override func forwardingTargetForSelector(aSelector: Selector)
-> AnyObject?
{
if middleMan?.respondsToSelector(aSelector) == true &&
doesSelectorBelongToAnyInterceptedProtocol(aSelector)
{
return middleMan
}
if receiver?.respondsToSelector(aSelector) == true {
return receiver
}
return super.forwardingTargetForSelector(aSelector)
}
/// Returns a Boolean value that indicates whether the receiver implements
/// or inherits a method that can respond to a specified message.
public override func respondsToSelector(aSelector: Selector) -> Bool {
if middleMan?.respondsToSelector(aSelector) == true &&
doesSelectorBelongToAnyInterceptedProtocol(aSelector)
{
return true
}
if receiver?.respondsToSelector(aSelector) == true {
return true
}
return super.respondsToSelector(aSelector)
}
/**
Create a protocol interceptor which intercepts a single Objecitve-C
protocol.
- Parameter protocols: An Objective-C protocol, such as
UITableViewDelegate.self.
*/
public class func forProtocol(aProtocol: Protocol)
-> NSProtocolInterceptor
{
return forProtocols([aProtocol])
}
/**
Create a protocol interceptor which intercepts a variable-length sort of
Objecitve-C protocols.
- Parameter protocols: A variable length sort of Objective-C protocol,
such as UITableViewDelegate.self.
*/
public class func forProtocols(protocols: Protocol ...)
-> NSProtocolInterceptor
{
return forProtocols(protocols)
}
/**
Create a protocol interceptor which intercepts an array of Objecitve-C
protocols.
- Parameter protocols: An array of Objective-C protocols, such as
[UITableViewDelegate.self].
*/
public class func forProtocols(protocols: [Protocol])
-> NSProtocolInterceptor
{
let protocolNames = protocols.map { NSStringFromProtocol($0) }
let sortedProtocolNames = protocolNames.sort()
let concatenatedName = sortedProtocolNames.joinWithSeparator(",")
let theConcreteClass = concreteClassWithProtocols(protocols,
concatenatedName: concatenatedName,
salt: nil)
let protocolInterceptor = theConcreteClass.init()
as! NSProtocolInterceptor
protocolInterceptor._interceptedProtocols = protocols
return protocolInterceptor
}
/**
Return a subclass of `NSProtocolInterceptor` which conforms to specified
protocols.
- Parameter protocols: An array of Objective-C protocols. The
subclass returned from this function will conform to these protocols.
- Parameter concatenatedName: A string which came from concatenating
names of `protocols`.
- Parameter salt: A UInt number appended to the class name
which used for distinguishing the class name itself from the duplicated.
- Discussion: The return value type of this function can only be
`NSObject.Type`, because if you return with `NSProtocolInterceptor.Type`,
you can only init the returned class to be a `NSProtocolInterceptor` but not
its subclass.
*/
private class func concreteClassWithProtocols(protocols: [Protocol],
concatenatedName: String,
salt: UInt?)
-> NSObject.Type
{
let className: String = {
let basicClassName = "_" +
NSStringFromClass(NSProtocolInterceptor.self) +
"_" + concatenatedName
if let salt = salt { return basicClassName + "_\(salt)" }
else { return basicClassName }
}()
let nextSalt = salt.map {$0 + 1}
if let theClass = NSClassFromString(className) {
switch theClass {
case let anInterceptorClass as NSProtocolInterceptor.Type:
let isClassConformsToAllProtocols: Bool = {
// Check if the found class conforms to the protocols
for eachProtocol in protocols
where !class_conformsToProtocol(anInterceptorClass,
eachProtocol)
{
return false
}
return true
}()
if isClassConformsToAllProtocols {
return anInterceptorClass
} else {
return concreteClassWithProtocols(protocols,
concatenatedName: concatenatedName,
salt: nextSalt)
}
default:
return concreteClassWithProtocols(protocols,
concatenatedName: concatenatedName,
salt: nextSalt)
}
} else {
let subclass = objc_allocateClassPair(NSProtocolInterceptor.self,
className,
0)
as! NSObject.Type
for eachProtocol in protocols {
class_addProtocol(subclass, eachProtocol)
}
objc_registerClassPair(subclass)
return subclass
}
}
}
/**
Returns true when the given selector belongs to the given protocol.
*/
public func sel_belongsToProtocol(aSelector: Selector,
_ aProtocol: Protocol) -> Bool
{
for optionBits: UInt in 0..<(1 << 2) {
let isRequired = optionBits & 1 != 0
let isInstance = !(optionBits & (1 << 1) != 0)
let methodDescription = protocol_getMethodDescription(aProtocol,
aSelector, isRequired, isInstance)
if !objc_method_description_isEmpty(methodDescription)
{
return true
}
}
return false
}
public func objc_method_description_isEmpty(
var methodDescription: objc_method_description)
-> Bool
{
let ptr = withUnsafePointer(&methodDescription) { UnsafePointer<Int8>($0) }
for offset in 0..<sizeof(objc_method_description) {
if ptr[offset] != 0 {
return false
}
}
return true
}