iOS Hook 崩溃

0x00 崩溃重现

被 Hook 的类，是这样的：

@interface ViewController : UIViewController
@end@implementation ViewController
- (void)loadView {[super loadView];NSLog(@"%s", __func__);
}- (void)test {NSLog(@"%s", __func__);
}- (void)viewDidLoad {[super viewDidLoad];[self test];
}@end

写的 Hook 逻辑是这样的：

@interface Hook : NSObject
@end#import <objc/runtime.h>
@implementation Hook+ (void)load {NSLog(@"%s", __func__);Class class = NSClassFromString(@"ViewController");Method originalMethod = class_getInstanceMethod(class, NSSelectorFromString(@"loadView"));Method swizzledMethod = class_getInstanceMethod([self class], NSSelectorFromString(@"swizzled_loadView"));method_exchangeImplementations(originalMethod, swizzledMethod);
}- (void)swizzled_loadView {NSLog(@"%s", __func__);[self swizzled_loadView];
}@end

真机运行后，是这样的，直接崩溃：

+[Hook load]
-[Hook swizzled_loadView]
-[ViewController swizzled_loadView]: unrecognized selector sent to instance 0x102e08dd0
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[ViewController swizzled_loadView]: unrecognized selector sent to instance 0x102e08dd0'

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0x00 换个方式

写的 Hook 逻辑是这样的：

@interface UIViewController (Hook)
@end#import <objc/runtime.h>
@implementation UIViewController (Hook)+ (void)load {NSLog(@"%s", __func__);Class class = NSClassFromString(@"ViewController");Method originalMethod = class_getInstanceMethod(class, NSSelectorFromString(@"loadView"));Method swizzledMethod = class_getInstanceMethod([self class], NSSelectorFromString(@"swizzled_loadView"));method_exchangeImplementations(originalMethod, swizzledMethod);
}- (void)swizzled_loadView {NSLog(@"%s", __func__);[self swizzled_loadView];UIView *view = [[UIView alloc] init];view. frame = CGRectMake (100, 200, 200, 200);view.backgroundColor = [UIColor redColor];[self.view addSubview:view];
}@end

真机运行后，不崩溃了：

+[UIViewController(Hook) load]
-[UIViewController(Hook) swizzled_loadView]
-[ViewController loadView]
-[ViewController test]

并且成功，添加了 view

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