Can the police detect blue text messages on Apple phones?

The public security bureau can check the content of the text message.

Article 148 of the "Criminal Procedure Law" stipulates: After filing a case, the public security organs shall investigate crimes endangering national security, terrorist activities, organized crimes of a mafia nature, major drug crimes or other serious harm. For social criminal cases, technical investigation measures can be taken after strict approval procedures according to the needs of criminal investigation.

After filing a case, the People's Procuratorate may, based on the needs of investigating the crime and subject to strict approval procedures, take measures to deal with major corruption and bribery criminal cases as well as major criminal cases that seriously infringe on citizens' personal rights by using their powers. Technical investigation measures shall be handed over to relevant authorities for implementation in accordance with regulations.

To pursue fugitive criminal suspects and defendants who are wanted or have been approved or decided to arrest, upon approval, technical investigation measures necessary for the pursuit can be taken.