IOS 防止Crash 组件WTSafeGuard
背景
由于Object-C本身的不安全性,导致很容易产生Crash。在这些Crash,很多我们可以利用自定义手段,进行避免。这样可以降低线上版本的Crash率,提升用户
体验。WTSafeGuard 避免APP Crash 组件,目前能做到的还很有限。
UIKit Called on Non-Main Thread
UIKit不是线程安全的,执行UIKit操作如果不在主线程很可能造成程序Crash。所以我们对Hook,UIView 的setNeedsLayout,layoutIfNeeded,layoutSubviews,setNeedsUpdateConstraints方法。如果执行以上函数没有在主队列,通过强行将执行代码,在主队列执行。
- (void)wt_safe_setNeedsLayout
{
if(![NSThread isMainThread]){
dispatch_async(dispatch_get_main_queue(), ^{
NSAssert(false, @"wt_safe_setNeedsLayout failed");
[self wt_safe_setNeedsLayout];
});
}else{
[self wt_safe_setNeedsLayout];
}
}
- (void)wt_safe_layoutIfNeeded
{
if(![NSThread isMainThread]){
dispatch_async(dispatch_get_main_queue(), ^{
NSAssert(false, @"wt_safe_layoutIfNeeded failed");
[self wt_safe_layoutIfNeeded];
});
}else{
[self wt_safe_layoutIfNeeded];
}
}
- (void)wt_safe_layoutSubviews
{
if(![NSThread isMainThread]){
dispatch_async(dispatch_get_main_queue(), ^{
NSAssert(false, @"wt_safe_layoutSubviews failed");
[self wt_safe_layoutSubviews];
});
}else{
[self wt_safe_layoutSubviews];
}
}
- (void)wt_safe_setNeedsUpdateConstraints
{
if(![NSThread isMainThread]){
dispatch_async(dispatch_get_main_queue(), ^{
NSAssert(false, @"wt_safe_setNeedsUpdateConstraints failed");
[self wt_safe_setNeedsUpdateConstraints];
});
}else{
[self wt_safe_setNeedsUpdateConstraints];
}
}
避免 Foundation 类Carsh
NSString
+ (instancetype)stringWithUTF8String:(const char *)bytes
- (instancetype)initWithString:(NSString *)aString
- (instancetype)initWithUTF8String:(const char *)nullTerminatedCString
- (instancetype)initWithFormat:(NSString *)format locale:(id)locale arguments:(va_list)argList
- (NSString *)stringByAppendingString:(NSString *)aString
- (unichar)characterAtIndex:(NSUInteger)index
- (void)getCharacters:(unichar *)buffer range:(NSRange)range
- (NSRange)rangeOfCharacterFromSet:(NSCharacterSet *)searchSet
options:(NSStringCompareOptions)mask
range:(NSRange)searchRange
- (NSRange)rangeOfString:(NSString *)searchString
options:(NSStringCompareOptions)mask
range:(NSRange)searchRange
locale:(NSLocale *)locale
- (NSString *)substringFromIndex:(NSUInteger)from
- (NSString *)substringWithRange:(NSRange)range
- (NSString *)substringToIndex:(NSUInteger)to
- (void)getLineStart:(NSUInteger *)startPtr
end:(NSUInteger *)lineEndPtr
contentsEnd:(NSUInteger *)contentsEndPtr
forRange:(NSRange)range
NSAttributedString
hook 方法:对传入参数range 进行check,如果range有问题,直接返回nil
- (NSAttributedString *)attributedSubstringFromRange:(NSRange)range;
NSFileManager
- (nullable NSDirectoryEnumerator<NSURL *> *)enumeratorAtURL:(NSURL *)url includingPropertiesForKeys:(nullable NSArray<NSURLResourceKey> *)keys options:(NSDirectoryEnumerationOptions)mask errorHandler:(nullable BOOL (^)(NSURL *url, NSError *error))handler
NSIndexPath
- (void)getIndexes:(NSUInteger *)indexes range:(NSRange)positionRang
NSJSONSerialization
+ (NSData *)dataWithJSONObject:(id)obj options:(NSJSONWritingOptions)opt error:(NSError **)error
NSDictionary
hook 方法:
+ (id)sharedKeySetForKeys:(NSArray<KeyType <NSCopying>> *)keys
- (instancetype)initWithObjects:(const ObjectType _Nonnull [_Nullable])objects forKeys:(const KeyType <NSCopying> _Nonnull [_Nullable])keys
- (instancetype)initWithObjects:(const ObjectType _Nonnull [_Nullable])objects forKeys:(const KeyType <NSCopying> _Nonnull [_Nullable])keys count:(NSUInteger)cnt
NSMutableDictionary
hook 方法:
+ (NSMutableDictionary<KeyType, ObjectType> *)dictionaryWithSharedKeySet:(id)keyset
- (void)setObject:(ObjectType)anObject forKey:(KeyType <NSCopying>)aKey;
- (void)removeObjectForKey:(KeyType)aKey;
NSSet
- (instancetype)WT_initWithObjects:(const id [])objects count:(NSUInteger)cnt
- (void)addObject:(id)object;
- (void)makeObjectsPerformSelector:(SEL)aSelector
- (void)makeObjectsPerformSelector:(SEL)aSelector
withObject:(id)argument
NSMutableSet
- (void)addObject:(id)anObject
NSMutableString
- (void)setString:(NSString *)aString
- (void)appendString:(NSString *)aString
- (void)deleteCharactersInRange:(NSRange)range
- (void)insertString:(NSString *)aString atIndex:(NSUInteger)loc
- (void)replaceCharactersInRange:(NSRange)range withString:(NSString *)aString
- (NSUInteger)replaceOccurrencesOfString:(NSString *)target
withString:(NSString *)replacement
options:(NSStringCompareOptions)options
range:(NSRange)searchRange
NSURL
+ (NSURL *)fileURLWithPath:(NSString *)path
+ (NSURL *)fileURLWithPath:(NSString *)path isDirectory:(BOOL)isDir
+ (NSURL *)fileURLWithPathComponents:(NSArray<NSString *> *)components
+ (NSURL *)fileURLWithPath:(NSString *)path
isDirectory:(BOOL)isDir
relativeToURL:(NSURL *)baseURL
- (instancetype)initWithString:(NSString *)URLString relativeToURL:(NSURL *)baseURL
- (instancetype)initFileURLWithPath:(NSString *)path
- (instancetype)initFileURLWithPath:(NSString *)path
relativeToURL:(NSURL *)baseURL
- (instancetype)initFileURLWithPath:(NSString *)path
isDirectory:(BOOL)isDir
relativeToURL:(NSURL *)baseURL
- KVO
- 容器越界(NSArray, NSDictionary,...)
- unrecognized selector crash (这个很多时候是由于class使用错误导致)
- NSTimer 导致crash
KVO Crash
项目中KVO crash 占比很高, 主要原因为,添加删除不对称导致。
解决方法为,添加Map进行缓存。
不过这个方案,目前还有缺陷。
unrecognized selector crash
这个就比较简单了,直接上代码:
[NSObject jr_swizzleMethod:@selector(forwardingTargetForSelector:) withMethod:@selector(WT_safeForwardingTargetForSelector:) error:&error];
- (id)WT_safeForwardingTargetForSelector:(SEL)aSelector
{
NSMethodSignature *signature = [self methodSignatureForSelector:aSelector];
if ([self respondsToSelector:aSelector] || signature) {
return [self WT_safeForwardingTargetForSelector:aSelector];
}
return [WTSafeGuard createFakeForwardTargetObject:self selector:aSelector];
}
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