查看bugly，好多崩溃由于莫名原因数组越界或者取超出数组范围内容，亦或set nil for key 了，针对这些增加几个category来避免直接崩的情况，提升用户体验。
一、NSArray:
创建NSArray的扩展类，NSArray+Extension。重写load方法，通过runtime 交换方法来实现。
+(void)load
{
staticdispatch_once_tonceToken;
dispatch_once(&onceToken, ^{
// objectindex
MethodoldObjectAtIndex =class_getInstanceMethod(objc_getClass("__NSArrayI"),@selector(objectAtIndex:));
MethodnewObjectAtIndex =class_getInstanceMethod(objc_getClass("__NSArrayI"),@selector(objectAtSafeIndex:));
method_exchangeImplementations(oldObjectAtIndex, newObjectAtIndex);
// arr[4]
MethodoldObjectAtIndex1 =class_getInstanceMethod(objc_getClass("__NSArrayI"),@selector(objectAtIndexedSubscript:));
MethodnewObjectAtIndex1 = class_getInstanceMethod(objc_getClass("__NSArrayI"),@selector(safeobjectAtIndexedSubscript:));
method_exchangeImplementations(oldObjectAtIndex1, newObjectAtIndex1);
});
}
因为，数组取值可以用objectindex 和 arr[index]两种方式，所以需要这两种方法都需要替换。
- (id)objectAtSafeIndex:(NSUInteger)index
{
if(index >self.count-1|| !self.count) {
@try{
return[selfobjectAtSafeIndex:index];
}
@catch(NSException *exception) {
NSLog(@"exception: %@", exception.reason);
returnnil;
}
}else{
return[selfobjectAtSafeIndex:index];
}
}
- (instancetype)safeobjectAtIndexedSubscript:(NSUInteger)index{
if(index > (self.count-1)) {// 数组越界
returnnil;
}else{// 没有越界
return [self safeobjectAtIndexedSubscript:index];
}
}
二、NSMutableArray+Extension。。。同理，可变数组如下：
+(void)load //第一次加载内存的时候会自动调用。
{
staticdispatch_once_tonceToken;
dispatch_once(&onceToken, ^{
//addObject
MethodorginalMethod =class_getInstanceMethod(NSClassFromString(@"__NSArrayM"),@selector(addObject:));
MethodnewMethod =class_getInstanceMethod(NSClassFromString(@"__NSArrayM"),@selector(gp_addobjc:));
method_exchangeImplementations(orginalMethod, newMethod);
//替换objectAtIndex方法
MethodoldMutableObjectAtIndex =class_getInstanceMethod(objc_getClass("__NSArrayM"),@selector(objectAtIndex:));
MethodnewMutableObjectAtIndex = class_getInstanceMethod(objc_getClass("__NSArrayM"),@selector(mutableObjectAtSafeIndex:));
method_exchangeImplementations(oldMutableObjectAtIndex, newMutableObjectAtIndex);
//替换arr[4]方法
MethodoldMutableObjectAtIndex1 =class_getInstanceMethod(objc_getClass("__NSArrayM"),@selector(objectAtIndexedSubscript:));
MethodnewMutableObjectAtIndex1 = class_getInstanceMethod(objc_getClass("__NSArrayM"),@selector(safeobjectAtIndexedSubscript:));
method_exchangeImplementations(oldMutableObjectAtIndex1, newMutableObjectAtIndex1);
});
}
//addobject
-(void)gp_addobjc:(id)object
{
if(object !=nil) {
[self gp_addobjc:object];//此时 方法交换，所以不能在这写addobject。若这样的话，会造成死循环。
}
}
//objectAtIndex
- (id)mutableObjectAtSafeIndex:(NSUInteger)index
{
if(index >self.count-1|| !self.count) {
@try{
return [self mutableObjectAtSafeIndex:index];
}
@catch(NSException *exception) {
NSLog(@"exception: %@", exception.reason);
returnnil;
}
}else{
return [self mutableObjectAtSafeIndex:index];
}
}
//aar[index]
- (instancetype)safeobjectAtIndexedSubscript:(NSUInteger)index{
if(index > (self.count-1)) {// 数组越界
returnnil;
}else{// 没有越界
return [self safeobjectAtIndexedSubscript:index];
}
}
