Runtime usage Collections

One. Exchange two methods.

Example 1:

static void Exchangedmethod (sel originalselector, sel Swizzledselector, class Class) {
    
    Method Originalmethod = Class_ Getinstancemethod (class, originalselector);
    Method Swizzledmethod = Class_getinstancemethod (class, swizzledselector);
    
    BOOL Didaddmethod =
    Class_addmethod (class,
                    originalselector,
                    method_getimplementation (Swizzledmethod ),
                    method_gettypeencoding (Swizzledmethod));
    
    if (didaddmethod) {
        Class_replacemethod (class,
                            swizzledselector,
                            method_getimplementation ( Originalmethod),
                            method_gettypeencoding (Originalmethod));
    }
    else {
        method_exchangeimplementations (Originalmethod, Swizzledmethod);
    }
}

+ (void) load {

    static dispatch_once_t Oncetoken;
    Dispatch_once (&oncetoken, ^{
        class = [self class];
        
        Exchangedmethod (@selector (layoutsubviews), @selector (s_layoutsubviews), Class);
        Exchangedmethod (@selector (hittest:withevent:), @selector (s_hittest:withevent:), Class);
        Exchangedmethod (@selector (touchesbegan:withevent:), @selector (s_touchesbegan:withevent:), Class);
    });
}

Example 2:

@implementation Uiviewcontroller (Tracking) + (void) load {static dispatch_once_t Oncetoken;

        Dispatch_once (&oncetoken, ^{class = [self class];
        SEL originalselector = @selector (viewwillappear:);

        SEL swizzledselector = @selector (xxx_viewwillappear:);
        Method Originalmethod = Class_getinstancemethod (class, Originalselector);

        Method Swizzledmethod = Class_getinstancemethod (class, Swizzledselector);
        If the swizzling is a class method, use the following method://Class class = Object_getclass ((id) self);
        ...//Method Originalmethod = Class_getclassmethod (class, Originalselector);

        Method Swizzledmethod = Class_getclassmethod (class, Swizzledselector);
    Exchange Implementation Method_exchangeimplementations (Originalmethod, Swizzledmethod);
});
    } #pragma mark-method swizzling-(void) Xxx_viewwillappear: (BOOL) animated {[Self xxx_viewwillappear:animated];
NSLog (@ "viewwillappear:%@", self); }

Two. Add attributes to Category

The Objc_getassociatedobject method can take a variable of a class, even if the variable is a private variable. If the app uses a private variable, you can avoid the app being rejected by this method.

Nsobject+indiebandname.h
@interface nsobject (indiebandname)
@property (nonatomic, strong) NSString * Indiebandname;
@end

NSOBJECT+INDIEBANDNAME.M    
#import "Nsobject+extension.h"
#import <objc/runtime.h>
static const void *indiebandnamekey = &IndieBandNameKey;    
@implementation NSObject (indiebandname)
@dynamic indiebandname;

-(NSString *) indiebandname {
    return objc_getassociatedobject (self, indiebandnamekey);
}

-(void) Setindiebandname: (NSString *) indiebandname{
    objc_setassociatedobject (self, Indiebandnamekey, Indiebandname, objc_association_retain_nonatomic);
}

@end