If the screen striped and black spots whether it can guarantee?

If you bought your device less than a year ago, contact Apple Support, an Apple Store or an Apple Authorized Service Provider next to your place to get it serviced.

If your device is older than one year and you don't have Apple Care+, Apple can replace the screen, if you are willing to pay for it, or, if more hardware is damaged, replace the phone for a reduced price.

Screen repair service pricing

Repair and replacement costs depend on your iPhone model and your AppleCare product coverage. Apple will run a diagnostic test to determine whether your iPhone has experienced additional damage. If it has, or if it needs other repairs, you may need to pay an out-of-warranty service fee. Accidental damage isn't covered under the Apple One Year Limited Warranty.

Model	Screen repair cost
iPhone 6	$109
iPhone 6s, iPhone 6 Plus, iPhone 5s, iPhone 5c, iPhone 5	$129
iPhone 6s Plus	$149

Plus a $6.95 shipping fee, if required. Fees are in USD and exclude local tax. Pricing is for service through Apple. The final service fee we charge will be determined during testing. Pricing and terms vary for service through an Apple Authorized Service Provider.

Out-of-warranty repair service

If your repair isn’t covered by Apple’s One Year Limited Warranty, AppleCare+, or AppleCare Protection Plan, your iPhone might be eligible for out-of-warranty service. For example, liquid damage isn’t covered by warranty but might be eligible for out-of-warranty service. Some damage isn’t eligible at all, for example if your device has been broken into multiple pieces. See Apple’s Repair Terms and Conditions for complete details.
Read Apple’s Repair Terms and Conditions

Model	Out-of-warranty service fee	Battery service*
iPhone 6s Plus, iPhone 6 Plus	$329	$79 *available only if battery fails Apple’s diagnostic test
iPhone 6s, iPhone 6	$299
iPhone 5s, iPhone 5c, iPhone 5	$269
iPhone 4s	$199
iPhone 4, iPhone 3GS, iPhone 3G	$149

Plus a $6.95 shipping fee, if required. Fees are in USD and exclude local tax. Pricing is for service through Apple. The final service fee we charge will be determined during testing and may be less than the service fee listed above. Pricing and terms vary for service through an Apple Authorized Service Provider.

Out-of-warranty pricing varies for Apple accessories such as adapters and Apple iPhone cases. Contact your carrier, Apple, or an Apple Authorized Service Provider for more information.

copied from Service Answer Center - iPhone