A Tool for scan duplicate methods, verify method implementation, or force invoke the method!
DaidoujiChen
- Scan single class for duplicate methods in categories.
- Like scan single class, we also can scan all of them!
- Verify a method in a class(metaclass). Lookup the current implementation.
- Force to invoke a method. Can not be dodge, swizzling penetration.
If we want to check if there are any duplicate methods in NSString. Using [DaiMethodHelper scanClass:]
[DaiMethodHelper scanClass:[NSString class]];
output:
===== Duplicate in NSString =====
-iLoveDaidouji (0x10db6f5eb) in NSString(Daidouji3) from DaiMethodHelper
-iLoveDaidouji (0x10db6ea70) in NSString(Daidouji2) from DaiMethodHelper
-iLoveDaidouji (0x10db6ea50) in NSString(Daidouji1) from DaiMethodHelper
===== Duplicate in NSString =====
-_initWithUTF8String:maxLength: (0x10e7f9316) in NSString(UISafeInstantiators) from UIKit
-_initWithUTF8String:maxLength: (0x111055a1f) in NSString(BaseBoard) from BaseBoard
We found there are three methods named iLoveDaidouji in categories Daidouji1, Daidouji2 and Daidouji3.
In the runtime, which one will be invoked?
For this concern, DaiMethodHelper provide a method to verify. This method named [DaiMethodHelper verifyClass:selector:]
[DaiMethodHelper verifyClass:[NSString class] selector:@selector(iLoveDaidouji)];
output:
* -iLoveDaidouji (0x1022225eb) in NSString(Daidouji3) from DaiMethodHelper
-iLoveDaidouji (0x102221a70) in NSString(Daidouji2) from DaiMethodHelper
-iLoveDaidouji (0x102221a50) in NSString(Daidouji1) from DaiMethodHelper
As the output, runtime choose the method iLoveDaidouji in category Daidouji3.
Check it out!
NSString *string = [NSString new];
NSLog(@"%@", [string iLoveDaidouji]);
output:
2015-09-10 15:53:47.727 DaiMethodHelper[9259:212520] iLoveDaidouji3
Yes, it run on category Daidouji3 correctly. And then, is it possible to run the method in category Daidouji1?
In this case, by default, runtime never choose the method in category Daidouji1. We need to use a little trick to done it.
NSString *string = [NSString new];
NSLog(@"%@", [DaiMethodHelper perform:string selector:@selector(iLoveDaidouji) category:@"Daidouji1"]);
output:
found -iLoveDaidouji (0x109589a50) in NSString(Daidouji1) from DaiMethodHelper
2015-09-10 16:03:24.666 DaiMethodHelper[9391:219463] iLoveDaidouji1
The result show, we found a method -iLoveDaidouji in category Daidouji1. And perform it.
Finally we made a simple method swizzling in MainViewController. like
- (NSString *)swi2_iLoveDaidouji:(NSString *)input {
NSLog(@"SwizzlingDaidoujiCategory2");
- (NSString *)swi1_iLoveDaidouji:(NSString *)input {
NSLog(@"SwizzlingDaidoujiCategory1");
- (NSString *)iLoveDaidouji:(NSString *)input {
NSLog(@"OriginDaidouji");
return [NSString stringWithFormat:@"iLoveDaidouji+%@", input];
}
}
}
NSLog(@"%@", [self iLoveDaidouji:@"very much"]);
output:
2015-09-10 16:10:35.816 DaiMethodHelper[9510:224080] SwizzlingDaidoujiCategory2
2015-09-10 16:10:35.817 DaiMethodHelper[9510:224080] SwizzlingDaidoujiCategory1
2015-09-10 16:10:35.817 DaiMethodHelper[9510:224080] OriginDaidouji
2015-09-10 16:10:35.817 DaiMethodHelper[9510:224080] iLoveDaidouji+very much
The interesting thing is we can also use [DaiMethodHelper perform:selector:category:] pass through all whe swizzling.
NSLog(@"%@", [DaiMethodHelper perform:self selector:@selector(iLoveDaidouji:) category:nil, @"very much"]);
output:
swizzling by -swi2_iLoveDaidouji: (0x10992d130) in MainViewController(DaidoujiCategory2) from DaiMethodHelper
swizzling by -swi1_iLoveDaidouji: (0x10992adb0) in MainViewController(DaidoujiCategory1) from DaiMethodHelper
found -iLoveDaidouji: (0x10992ce40) in MainViewController from DaiMethodHelper
2015-09-10 16:19:03.590 DaiMethodHelper[9617:228273] OriginDaidouji
2015-09-10 16:19:03.591 DaiMethodHelper[9617:228273] iLoveDaidouji+very much
The method only run the original code. Ignore all the swizzle. Fun!
I am not sure apple allow the method invokeUsingIMP: in NSInvocation or not.