objective-c 避免数组越界，字典取不到值为空崩溃扩展方
@interface NSArray (Extend)
- (id)objectAtCheckedIndex:(int)index;
- (NSString *)stringAtCheckedIndex:(int)index;
@end
@interface NSDictionary (Extend)
- (id)objectForCheckedKey:(id)key;
- (NSString *)stringForCheckedKey:(id)key;
@end
//检查index是否超过总大小
- (id)objectAtCheckedIndex:(int)index
{
if ([self count] <= index) {
// DLog(@"NSArray数据超过容量");
return nil;
}
else if (index <= -1) {
// DLog(@"index 错误");
return nil;
}
else
{
return [self objectAtIndex:index];
}
}
- (NSString *)stringAtCheckedIndex:(int)index
{
if ([self count] <= index) {
// DLog(@"NSArray数据超过容量");
return @"";
}
else if (index <= -1) {
// DLog(@"index 错误");
return @"";
}
else
{
return (NSString *)[self objectAtIndex:index];
}
}
@end
@implementation NSDictionary (Extend)
- (id)objectForCheckedKey:(id)key
{
id object_ = [self objectForKey:key];
if ([object_ isKindOfClass:[NSNull class] ]) {
return nil;
}
return object_;
}
- (NSString *)stringForCheckedKey:(id)key
{
id object_ = [self objectForKey:key];
if ([object_ isKindOfClass:[NSString class] ]) {
return object_;
}
if([object_ isKindOfClass:[NSNumber class] ]) {
return [object_ stringValue];
}
else if ([object_ isKindOfClass:[NSString class] ]) {
return @"";
}
else
{
return @"";
}
}
@end
使用stringForCheckedKey，objectForCheckedKey来取字典便不会崩溃，使用objectAtCheckedIndex，stringAtCheckedIndex便不会越界
