iOS 数组越界 Crash处理经验

标签：ios   经验   

我们先来看看有可能会出现的数组越界Crash的地方；

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    WelfareItem *item = [_datasourceArray objectAtIndex:indexPath.row];//有可能会越界，你在下拉刷新时会用[_datasourceArray removeAllObjects]，这时你又点了某个cell就会Crash
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    WelfareItem *item = _datasourceArray[indexPath.row];//有可能会越界，两个地方用了[tableView reloadData]；后一个有[_datasourceArray removeAllObjects]；前一个还没有执行完，就会Crash
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    WelfareItem *item = nil;
    if (indexPath.row < [_datasourceArray count]) {//无论你武功有多高，有时也会忘记加
        item = [_datasourceArray objectAtIndex:indexPath.row];
    }
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    WelfareItem *item = nil;
    if (indexPath.row < [_datasourceArray count]) {
        item = [_datasourceArray objectAtIndex:indexPath.row];
    }
}

/*!
 @category 
 @abstract NSObject的Category
 */
@interface NSObject (Util)

/*!
@method swizzleMethod:withMethod:error:
@abstract 对实例方法进行替换
@param oldSelector 想要替换的方法
@param newSelector 实际替换为的方法
@param error 替换过程中出现的错误，如果没有错误为nil
*/
+ (BOOL)swizzleMethod:(SEL)originalSelector withMethod:(SEL)swizzledSelector error:(NSError **)error;

@end


#import "NSObject+Util.h"
#import <objc/runtime.h>

@implementation NSObject (Util)

+ (BOOL)swizzleMethod:(SEL)originalSelector withMethod:(SEL)swizzledSelector error:(NSError **)error
{
    Method originalMethod = class_getInstanceMethod(self, originalSelector);
    if (!originalMethod) {
        NSString *string = [NSString stringWithFormat:@" %@ 类没有找到 %@ 方法",NSStringFromClass([self class]),NSStringFromSelector(originalSelector)];
		*error = [NSError errorWithDomain:@"NSCocoaErrorDomain" code:-1 userInfo:[NSDictionary dictionaryWithObject:string forKey:NSLocalizedDescriptionKey]];
        return NO;
    }
    
    Method swizzledMethod = class_getInstanceMethod(self, swizzledSelector);
    if (!swizzledMethod) {
        NSString *string = [NSString stringWithFormat:@" %@ 类没有找到 %@ 方法",NSStringFromClass([self class]),NSStringFromSelector(swizzledSelector)];
		*error = [NSError errorWithDomain:@"NSCocoaErrorDomain" code:-1 userInfo:[NSDictionary dictionaryWithObject:string forKey:NSLocalizedDescriptionKey]];
        return NO;
    }
    
    if (class_addMethod(self, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod))) {
        class_replaceMethod(self, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod));
    }
    else {
        method_exchangeImplementations(originalMethod, swizzledMethod);
    }
    
    return YES;
}

@end


@implementation NSArray (ErrerManager)

+ (void)load
{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        @autoreleasepool
        {
            [objc_getClass("__NSArrayI") swizzleMethod:@selector(objectAtIndex:) withMethod:@selector(swizzleObjectAtIndex:) error:nil];
            [objc_getClass("__NSArrayM") swizzleMethod:@selector(objectAtIndex:) withMethod:@selector(swizzleObjectAtIndex:) error:nil];
        };
    });
}

- (id)swizzleObjectAtIndex:(NSUInteger)index
{
    if (index < self.count)
    {
        return [self swizzleObjectAtIndex:index];
    }
    NSLog(@"%@ 越界",self);
    return nil;//越界返回为nil
}

@end

1 tbreader 0x002b93e9 tbreader + 2098153
2 libsystem_platform.dylib 0x33a66873 _sigtramp + 34
3 libsystem_blocks.dylib 0x33941ae1 _Block_release + 216
4 libobjc.A.dylib 0x333c11a9 + 404
5 CoreFoundation 0x25ba23a9 _CFAutoreleasePoolPop + 16
6 UIKit 0x2912317f + 42
7 CoreFoundation 0x25c565cd + 20
8 CoreFoundation 0x25c53c8b + 278
9 CoreFoundation 0x25c54093 + 914
10 CoreFoundation 0x25ba2621 CFRunLoopRunSpecific + 476
11 CoreFoundation 0x25ba2433 CFRunLoopRunInMode + 106
12 GraphicsServices 0x2cf0a0a9 GSEventRunModal + 136
13 UIKit 0x2918c809 UIApplicationMain + 1440

@interface NSArray (SHYUtil)

/*!
 @method objectAtIndexCheck:
 @abstract 检查是否越界和NSNull如果是返回nil
 @result 返回对象
 */
- (id)objectAtIndexCheck:(NSUInteger)index;

@end


#import "NSArray+SHYUtil.h"

@implementation NSArray (SHYUtil)

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

@end

iOS 数组越界 Crash处理经验

标签：ios   经验   

原文地址：http://blog.csdn.net/jxncwzb/article/details/44829925