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GTXSwizzler.m
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GTXSwizzler.m
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//
// Copyright 2020 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#import "GTXSwizzler.h"
#import "GTXAssertions.h"
#import <objc/runtime.h>
@implementation GTXSwizzler
+ (void)addInstanceMethod:(SEL)methodSelector fromClass:(Class)srcClass toClass:(Class)destClass {
Method instanceMethod = class_getInstanceMethod(srcClass, methodSelector);
const char *typeEncoding = method_getTypeEncoding(instanceMethod);
NSAssert(typeEncoding, @"Failed to get method type encoding.");
BOOL success = class_addMethod(destClass, methodSelector,
method_getImplementation(instanceMethod), typeEncoding);
NSAssert(success, @"Failed to add %@ from %@ to %@", NSStringFromSelector(methodSelector),
srcClass, destClass);
(void)success; // Ensures 'success' is marked as used even if NSAssert is removed.
}
+ (void)swizzleInstanceMethod:(SEL)methodSelector1
withMethod:(SEL)methodSelector2
inClass:(Class)clazz {
Method method1 = class_getInstanceMethod(clazz, methodSelector1);
Method method2 = class_getInstanceMethod(clazz, methodSelector2);
// Only swizzle if both methods are found
if (method1 && method2) {
IMP imp1 = method_getImplementation(method1);
IMP imp2 = method_getImplementation(method2);
if (class_addMethod(clazz, methodSelector1, imp2, method_getTypeEncoding(method2))) {
class_replaceMethod(clazz, methodSelector2, imp1, method_getTypeEncoding(method1));
} else {
method_exchangeImplementations(method1, method2);
}
} else {
GTX_ASSERT(NO, @"Cannot swizzle %@", NSStringFromSelector(methodSelector1));
}
}
@end