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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,48 @@ | ||
| // | ||
| // NSObject+MELazyPropertySwizzlingAdditions.h | ||
| // Gedcom | ||
| // | ||
| // Created by Mikkel Eide Eriksen on 24/04/13. | ||
| // Copyright (c) 2013 Mikkel Eide Eriksen. All rights reserved. | ||
| // | ||
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| #import <Foundation/Foundation.h> | ||
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| /** | ||
| Usage: Add this protocol to a class | ||
| For each property that you wish to load lazily, implement the following lazy getter: | ||
| ``` | ||
| - (id)_lazy<PropertyName> | ||
| { | ||
| return <LazyPropertyValue>; | ||
| } | ||
| ``` | ||
| Additionally, create an ivar: | ||
| ``` | ||
| @implementation MyClass { | ||
| dispatch_once_t _lazy<PropertyName>Token; | ||
| } | ||
| //... | ||
| @end | ||
| ``` | ||
| That's it, you're done. The first time a property is accessed, the _lazy getter is called in to set the ivar. Subsequently, the getters & setters are used as normal. | ||
| */ | ||
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| static const char lazyPrefix[] = "_lazy"; | ||
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| @protocol MELazyPropertySwizzling <NSObject> | ||
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| @end | ||
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| @interface NSObject (MELazyPropertySwizzlingAdditions) | ||
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| @end |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,94 @@ | ||
| // | ||
| // NSObject+MELazyPropertySwizzlingAdditions.m | ||
| // Gedcom | ||
| // | ||
| // Created by Mikkel Eide Eriksen on 24/04/13. | ||
| // Copyright (c) 2013 Mikkel Eide Eriksen. All rights reserved. | ||
| // | ||
|
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| #import "NSObject+MELazyPropertySwizzlingAdditions.h" | ||
| #import <objc/runtime.h> | ||
| #import <string.h> | ||
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| @implementation NSObject (MELazyPropertySwizzlingAdditions) | ||
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| + (void)load | ||
| { | ||
| const size_t prefixLen = strlen(lazyPrefix); | ||
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| int numClasses; | ||
| Class *classes = NULL; | ||
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| classes = NULL; | ||
| numClasses = objc_getClassList(NULL, 0); | ||
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| if (numClasses > 0 ) | ||
| { | ||
| classes = (__unsafe_unretained Class *)malloc(sizeof(Class) * numClasses); | ||
| numClasses = objc_getClassList(classes, numClasses); | ||
| for (int i = 0; i < numClasses; i++) { | ||
| Class cls = classes[i]; | ||
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| if (!class_conformsToProtocol(cls, @protocol(MELazyPropertySwizzling))) { | ||
| continue; | ||
| } | ||
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| int unsigned numMethods; | ||
| Method *methods = class_copyMethodList(cls, &numMethods); | ||
| for (int i = 0; i < numMethods; i++) { | ||
| SEL lazySel = method_getName(methods[i]); | ||
| const char *lazySelName = sel_getName(lazySel); | ||
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| if (strncmp(lazyPrefix, lazySelName, prefixLen) != 0) { | ||
| continue; | ||
| } | ||
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| //NSLog(@"%s", lazySelName); | ||
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| size_t tmpSize = strlen(lazySelName)-prefixLen; | ||
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| char *getterName = malloc(tmpSize * sizeof(char)); | ||
| strncpy(getterName, lazySelName+prefixLen, tmpSize); | ||
| getterName[0] = getterName[0] + 32; // lowercase first char | ||
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| char *ivarName = malloc((tmpSize+1) * sizeof(char)); | ||
| strncpy(ivarName+1, getterName, tmpSize); | ||
| ivarName[0] = '_'; | ||
| ivarName[tmpSize+1] = '\0'; | ||
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| tmpSize = strlen(lazySelName); | ||
| char *tokenName = malloc((tmpSize+5) * sizeof(char)); | ||
| strncpy(tokenName, lazySelName, tmpSize); | ||
| strncpy(tokenName+tmpSize, "Token", 5); | ||
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| SEL getterSel = sel_registerName(getterName); | ||
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| Ivar ivar = class_getInstanceVariable(cls, ivarName); | ||
| Ivar tokenIvar = class_getInstanceVariable(cls, tokenName); | ||
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| Method lazyGetter = class_getInstanceMethod(cls, lazySel); | ||
| Method origGetter = class_getInstanceMethod(cls, getterSel); | ||
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| IMP lazyIMP = method_getImplementation(lazyGetter); | ||
| IMP origIMP = method_getImplementation(origGetter); | ||
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| IMP newIMP = imp_implementationWithBlock(^(id _s) { | ||
| dispatch_once_t token = (dispatch_once_t)object_getIvar(_s, tokenIvar); | ||
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| dispatch_once(&token, ^{ | ||
| if (!object_getIvar(_s, ivar)) { | ||
| object_setIvar(_s, ivar, lazyIMP(_s, lazySel)); | ||
| } | ||
| }); | ||
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| return origIMP(_s, getterSel); | ||
| }); | ||
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| method_setImplementation(origGetter, newIMP); | ||
| } | ||
| } | ||
| free(classes); | ||
| } | ||
| } | ||
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| @end |