iOS-线程安全NSMutableArray+runtime

导读

当对一个可变数组操作很频繁,并且在多个线程操作同一个可变数组时,发生数组越界等奔溃是很常见的.所以使用runtime,对其方法进行交换.然后在交换方法中对增,删,改,查等做保护机制就可以避免类似情况发生.

部分源码解读

1.NSArray分类

1.新建一个NSArray的分类,在其.h文件中声明一些方法

@interface NSArray (SafeAccess)

-(id)objectWithIndex:(NSUInteger)index;

- (NSString*)stringWithIndex:(NSUInteger)index;

- (NSNumber*)numberWithIndex:(NSUInteger)index;

- (NSDecimalNumber *)decimalNumberWithIndex:(NSUInteger)index;

- (NSArray*)arrayWithIndex:(NSUInteger)index;

- (NSDictionary*)dictionaryWithIndex:(NSUInteger)index;

- (NSInteger)integerWithIndex:(NSUInteger)index;

- (float)floatWithIndex:(NSUInteger)index;

- (NSDate *)dateWithIndex:(NSUInteger)index dateFormat:(NSString *)dateFormat;

// CG
- (CGFloat)CGFloatWithIndex:(NSUInteger)index;

// Returns a reversed Array
- (NSArray *)Reverse;

/**
 Applies the callback to the elements of the given arrays.
 
 @return an new array containing all the elements of receiver after applying the callback function to each one.
 */
- (NSArray *)map:(id (^)(id obj))block;

/**
 Converts receiver to json string. return nil if an error occurs.
 */
- (NSString *)jsonString;

@end

2.其.m文件的实现

// 导入runtime.h文件
#import <objc/runtime.h>

在+(void)load方法中交换方法的实现

+ (void)load{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        // 1 添加空对象
        SEL safeAdd = @selector(GFS_safeAddObject:);
        SEL unsafeAdd = @selector(addObject:);
        
        Method originalSEL = class_getInstanceMethod(objc_getClass("__NSArrayM"), unsafeAdd);
        Method swizzleSEL = class_getInstanceMethod(objc_getClass("__NSArrayM"), safeAdd);
        
        BOOL didAddMethod = class_addMethod(self, unsafeAdd, method_getImplementation(swizzleSEL), method_getTypeEncoding(swizzleSEL));
        
        if (didAddMethod) {
            class_replaceMethod(self, safeAdd, method_getImplementation(originalSEL), method_getTypeEncoding(originalSEL));
        }else{
            method_exchangeImplementations(originalSEL, swizzleSEL);
        }
        
        // 2 数组越界
        SEL safeObjcAtIndex = @selector(GFS_safeObjcAtIndex:);
        SEL unsafeObjcAtIndex = @selector(objectAtIndex:);
        
        Class arryClass = NSClassFromString(@"__NSArrayI");
        Method originalObjcAtIndex = class_getInstanceMethod(arryClass, unsafeObjcAtIndex);
        Method swizzleObjcAtIndex = class_getInstanceMethod(arryClass, safeObjcAtIndex);
        method_exchangeImplementations(originalObjcAtIndex, swizzleObjcAtIndex);
    });
}

两个交换方法的实现

- (id)GFS_safeObjcAtIndex:(NSUInteger)index{
    if (self.count - 1 < index) {
        NSAssert(NO, @"beyond the boundary");
        return nil;
    }else{
        return [self GFS_safeObjcAtIndex:index];
    }
}

- (void)GFS_safeAddObject:(id)object{
    if (!object) {// objectt == nil
        NSAssert(NO, @"added a nil object");
    }else{
        [self GFS_safeAddObject:object];
    }
}

其他方法的实现

-(id)objectWithIndex:(NSUInteger)index{
    if (index >= [self count]) {
        return nil;
    }
    id value = self[(NSUInteger) index];
    if (value == [NSNull null]) {
        return nil;
    }
    return value;
}

- (NSString*)stringWithIndex:(NSUInteger)index{
    id value = [self objectWithIndex:index];
    if (value == nil || value == [NSNull null]){
        return @"";
    }
    if ([value isKindOfClass:[NSString class]]) {
        return (NSString*)value;
    }
    if ([value isKindOfClass:[NSNumber class]]) {
        return [value stringValue];
    }
    return nil;
}

- (NSNumber*)numberWithIndex:(NSUInteger)index{
    id value = [self objectWithIndex:index];
    if ([value isKindOfClass:[NSNumber class]]) {
        return (NSNumber*)value;
    }
    if ([value isKindOfClass:[NSString class]]) {
        NSNumberFormatter * f = [[NSNumberFormatter alloc] init];
        [f setNumberStyle:NSNumberFormatterDecimalStyle];
        return [f numberFromString:(NSString*)value];
    }
    return nil;
}

- (NSDecimalNumber *)decimalNumberWithIndex:(NSUInteger)index{
    id value = [self objectWithIndex:index];
    
    if ([value isKindOfClass:[NSDecimalNumber class]]) {
        return value;
    } else if ([value isKindOfClass:[NSNumber class]]) {
        NSNumber * number = (NSNumber*)value;
        return [NSDecimalNumber decimalNumberWithDecimal:[number decimalValue]];
    } else if ([value isKindOfClass:[NSString class]]) {
        NSString * str = (NSString*)value;
        return [str isEqualToString:@""] ? nil : [NSDecimalNumber decimalNumberWithString:str];
    }
    return nil;
}

- (NSArray*)arrayWithIndex:(NSUInteger)index{
    id value = [self objectWithIndex:index];
    if (value == nil || value == [NSNull null]){
        return nil;
    }
    if ([value isKindOfClass:[NSArray class]]){
        return value;
    }
    return nil;
}

- (NSDictionary*)dictionaryWithIndex:(NSUInteger)index{
    id value = [self objectWithIndex:index];
    if (value == nil || value == [NSNull null]){
        return nil;
    }
    if ([value isKindOfClass:[NSDictionary class]]){
        return value;
    }
    return nil;
}

- (NSInteger)integerWithIndex:(NSUInteger)index{
    id value = [self objectWithIndex:index];
    if (value == nil || value == [NSNull null]){
        return 0;
    }
    if ([value isKindOfClass:[NSString class]] || [value isKindOfClass:[NSNumber class]]){
        return [value integerValue];
    }
    return 0;
}

- (float)floatWithIndex:(NSUInteger)index{
    id value = [self objectWithIndex:index];
    
    if (value == nil || value == [NSNull null]){
        return 0;
    }
    if ([value isKindOfClass:[NSNumber class]] || [value isKindOfClass:[NSString class]]){
        return [value floatValue];
    }
    return 0;
}

- (NSDate *)dateWithIndex:(NSUInteger)index dateFormat:(NSString *)dateFormat {
    NSDateFormatter *formater = [[NSDateFormatter alloc]init];
    formater.dateFormat = dateFormat;
    id value = [self objectWithIndex:index];
    
    if (value == nil || value == [NSNull null]){
        return nil;
    }
    
    if ([value isKindOfClass:[NSString class]] && ![value isEqualToString:@""] && !dateFormat) {
        return [formater dateFromString:value];
    }
    return nil;
}

- (CGFloat)CGFloatWithIndex:(NSUInteger)index{
    id value = [self objectWithIndex:index];
    
    CGFloat f = [value doubleValue];
    return f;
}

- (NSArray *)Reverse{
    return self.reverseObjectEnumerator.allObjects;
}

- (NSArray *)map:(id  _Nonnull (^)(id _Nonnull))block{
    __block NSMutableArray *array = [NSMutableArray arrayWithCapacity:[self count]];
    [self enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
        [array addObject:block(obj)];
    }];
    return array;
}

- (NSString *)jsonString{
    if ([NSJSONSerialization isValidJSONObject:self]) {
        NSError *error;
        NSData *jsonData = [NSJSONSerialization dataWithJSONObject:self options:0 error:&error];
        NSString *json = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
        return json;
    }
    return nil;
}

---

2.NSMutableArray分类

.h文件声明

@interface NSMutableArray(SafeAccess)

-(void)addObj:(id)i;

-(void)addString:(NSString*)i;

-(void)addBool:(BOOL)i;

-(void)addInt:(int)i;

-(void)addInteger:(NSInteger)i;

-(void)addCGFloat:(CGFloat)f;

@end

.m文件实现方法

• +(void)load声明交换方法

+ (void)load {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        id obj = [[self alloc] init];
        [obj swizzleMethod:@selector(addObject:) withMethod:@selector(safeAddObject:)];
        [obj swizzleMethod:@selector(objectAtIndex:) withMethod:@selector(safeObjectAtIndex:)];
        [obj swizzleMethod:@selector(removeObjectAtIndex:) withMethod:@selector(safeRemoveObjectAtIndex:)];
        [obj swizzleMethod:@selector(replaceObjectAtIndex:withObject:) withMethod:@selector(safeReplaceObjectAtIndex:withObject:)];
        [obj swizzleMethod:@selector(removeObjectsInRange:) withMethod:@selector(safeRemoveObjectsInRange:)];
        [obj swizzleMethod:@selector(insertObject:atIndex:) withMethod:@selector(safeInsertObject:atIndex:)];
    });
}

- (void)swizzleMethod:(SEL)origSelector withMethod:(SEL)newSelector
{
    Class cls = [self class];
    
    Method originalMethod = class_getInstanceMethod(cls, origSelector);
    Method swizzledMethod = class_getInstanceMethod(cls, newSelector);
    
    BOOL didAddMethod = class_addMethod(cls,
                                        origSelector,
                                        method_getImplementation(swizzledMethod),
                                        method_getTypeEncoding(swizzledMethod));
    if (didAddMethod) {
        class_replaceMethod(cls,
                            newSelector,
                            method_getImplementation(originalMethod),
                            method_getTypeEncoding(originalMethod));
    } else {
        method_exchangeImplementations(originalMethod, swizzledMethod);
    }
}

• 交换方法的实现

- (id)safeObjectAtIndex:(NSUInteger)index {
    if (index >= self.count) {
        return nil;
    }
    return [self safeObjectAtIndex:index];
}

- (void)safeAddObject:(id)anObject {
    if (!anObject) {
        return;
    }
    [self safeAddObject:anObject];
}

- (void)safeRemoveObjectAtIndex:(NSUInteger)index {
    if (index >= [self count]) {
        return;
    }
    
    return [self safeRemoveObjectAtIndex:index];
}

- (void)safeReplaceObjectAtIndex:(NSUInteger)index withObject:(id)anObject {
    if (index >= [self count]) {
        return;
    }
    
    if (!anObject) {
        return;
    }
    
    [self safeReplaceObjectAtIndex:index withObject:anObject];
}

- (void)safeRemoveObjectsInRange:(NSRange)range {
    if (range.location > self.count) {
        return;
    }
    
    if (range.length > self.count) {
        return;
    }
    
    if ((range.location + range.length) > self.count) {
        return;
    }
    
    return [self safeRemoveObjectsInRange:range];
}

- (void)safeInsertObject:(id)anObject atIndex:(NSUInteger)index {
    if (index > self.count) {
        return;
    }
    
    if (!anObject) {
        return;
    }
    
    [self safeInsertObject:anObject atIndex:index];
}

• 其他方法的实现

-(void)addObj:(id)i{
    if ( i!= nil) {
        [self addObject:i];
    }
}

-(void)addString:(NSString*)i{
    if (i != nil) {
        [self addObject:i];
    }
}

-(void)addBool:(BOOL)i{
    [self addObject:@(i)];
}

-(void)addInt:(int)i{
    [self addObject:@(i)];
}

-(void)addInteger:(NSInteger)i{
    [self addObject:@(i)];
}

-(void)addCGFloat:(CGFloat)f{
    [self addObject:@(f)];
}

---

3.新建一个继承NSObjec的SyncMutableArray类,将其作为线程安全数组使用

原理: 将其所有操作,包括增,删,改,查全部放到同一个队列中同步执行,即可保证线程安全.

• SyncMutableArray.h文件中方法的声明

@interface SyncMutableArray : NSObject

- (void)addObject:(id)anObject;

- (void)addObjectsFromArray:(NSArray *)anArray;

- (void)insertObject:(id)anObject atIndex:(NSUInteger)index;

- (id)popFirstObject;

- (id)firstObject;

- (id)lastObject;

- (id)popLastObject;

- (void)removeLastObject;

- (void)removeObjectAtIndex:(NSUInteger)index;

- (void)removeObjectsAtIndexes:(NSIndexSet *)indexes;

- (void)removeObject:(id)anObject;

- (void)removeAllObjects;

- (void)replaceObjectAtIndex:(NSUInteger)index withObject:(id)anObject;

- (NSInteger)count;

- (BOOL)containsObject:(id)anObject;

- (id)objectAtIndex:(NSUInteger)index;

- (void)enumerateObjectsUsingBlock:(void (^)(id obj, NSUInteger idx, BOOL *stop))block;

- (NSMutableArray *)getArray;

@end

SyncMutableArray.m文件的实现

• 先声明一个可变数组和队列

@interface SyncMutableArray ()
@property(nonatomic, strong) NSMutableArray *array;
@property(nonatomic, strong) dispatch_queue_t dispatchQueue;
@end

• 在其初始化方法中给变量赋值

- (instancetype)init {
    if (self = [super init]) {
        _array = [NSMutableArray new];
        _dispatchQueue = dispatch_queue_create("com.banggood.banggoodSycmutableArray", DISPATCH_QUEUE_SERIAL);
    }
    return self;
}

• 然后实现可变数组的所有方法,并且在方法中进行同步操作并做保护措施

- (void)addObject:(id)anObject {
    dispatch_sync(_dispatchQueue, ^{
        if (!anObject) return;
        [_array addObject:anObject];
    });
}

- (void)addObjectsFromArray:(id)anArray {
    dispatch_sync(_dispatchQueue, ^{
        if (!anArray) return;
        [_array addObjectsFromArray:anArray];
    });
}

- (void)insertObject:(id)anObject atIndex:(NSUInteger)index {
    dispatch_sync(_dispatchQueue, ^{
        if (!anObject) return;
        [_array insertObject:anObject atIndex:index];
    });
}

- (id)popLastObject {
    __block id object;
    dispatch_sync(_dispatchQueue, ^{
        object = [_array lastObject];
        [_array removeLastObject];
    });
    return object;
}

- (void)removeLastObject {
    dispatch_sync(_dispatchQueue, ^{
        [_array removeLastObject];
    });
}

- (id)popFirstObject {
    __block id object;
    dispatch_sync(_dispatchQueue, ^{
        object = [_array firstObject];
        [_array removeLastObject];
    });
    return object;
}

- (id)firstObject {
    __block id object;
    dispatch_sync(_dispatchQueue, ^{
        object = [_array firstObject];
    });
    return object;
}

- (id)lastObject {
    __block id object;
    dispatch_sync(_dispatchQueue, ^{
        object = [_array lastObject];
    });
    return object;
}

- (void)removeAllObjects {
    dispatch_sync(_dispatchQueue, ^{
        [_array removeAllObjects];
    });
}

- (void)removeObjectAtIndex:(NSUInteger)index {
    dispatch_sync(_dispatchQueue, ^{
        [_array removeObjectAtIndex:index];
    });
}

- (void)removeObject:(id)anObject {
    dispatch_sync(_dispatchQueue, ^{
        if (!anObject) return;
        [_array removeObject:anObject];
    });
}

- (void)replaceObjectAtIndex:(NSUInteger)index withObject:(id)anObject {
    dispatch_sync(_dispatchQueue, ^{
        if (!anObject) return;
        _array[index] = anObject;
    });
}

- (void)removeObjectsAtIndexes:(NSIndexSet *)indexes {
    dispatch_sync(_dispatchQueue, ^{
        [_array removeObjectsAtIndexes:indexes];
    });
}

- (void)enumerateObjectsUsingBlock:(void (^)(id obj, NSUInteger idx, BOOL *stop))block {
    dispatch_sync(_dispatchQueue, ^{
        [_array enumerateObjectsUsingBlock:block];
    });
}

- (NSMutableArray *)getArray {
    __block NSMutableArray *temp;
    dispatch_sync(_dispatchQueue, ^{
        temp = _array;
    });
    return temp;
}

- (NSInteger)count {
    __block NSInteger returnObject = 0;
    dispatch_sync(_dispatchQueue, ^{
        returnObject = _array.count;
    });
    return returnObject;
}

- (BOOL)containsObject:(id)anObject {
    __block BOOL returnObject = NO;
    dispatch_sync(_dispatchQueue, ^{
        if (!anObject || ![_array isKindOfClass:[NSMutableArray class]]) return;
        returnObject = [_array containsObject:anObject];
    });
    return returnObject;
}

- (id)objectAtIndex:(NSUInteger)index {
    __block id returnObject = nil;
    dispatch_sync(_dispatchQueue, ^{
        if (_array.count > 0) {
            returnObject = [_array objectWithIndex:index];
        } else {
            returnObject = nil;
        }
    });
    return returnObject;
}

- (NSString *)debugDescription {
    return [NSString stringWithFormat:@"%@", _array];
}

---

使用

• 导入线程安全数组头文件

#import "SyncMutableArray.h"

• 然后写一个循环多次,多个子线程对可变数组进行增,删,改,查操作

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    [self syncMutableArray];
}

- (void)syncMutableArray {
    NSDate *startDate = [[NSDate alloc] init];
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    SyncMutableArray *safeArr = [[SyncMutableArray alloc] init];
    for ( int i = 0; i < 1000; i ++) {
        dispatch_async(queue, ^{
            NSLog(@"添加第%d个",i);
            [safeArr addObject:[NSString stringWithFormat:@"%d",i]];
        });
        
        dispatch_async(queue, ^{
            NSLog(@"删除第%d个",i);
            [safeArr removeObjectAtIndex:i];
        });
        
        dispatch_async(queue, ^{
            NSLog(@"读取第%d个数据:%@",i,[safeArr objectAtIndex:i]);
        });
    }
    
    NSDate *endDate = [[NSDate alloc] init];
    double time = [endDate timeIntervalSince1970] - [startDate timeIntervalSince1970];
    NSLog(@"执行时间:%f",time);
}

项目连接地址

总结

要想使多个线程操作同一个可变数组,并且并发量比较大的时候不会发生crash.可以采用runtime + 线程安全数组来实现.