When the lib is linked on iOS 7.0 I receive several linker warnings:

ld: warning: directory not found for option '-F/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator9.1.sdk/Developer/Library/Frameworks'
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/cpprest/libcpprest.a(uri.o)) was built for newer iOS version (9.1) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/cpprest/libcpprest.a(http_client_msg.o)) was built for newer iOS version (9.1) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/cpprest/libcpprest.a(http_client_asio.o)) was built for newer iOS version (9.1) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/cpprest/libcpprest.a(json.o)) was built for newer iOS version (9.1) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/boost.framework/boost(thread_thread.o)) was built for newer iOS version (8.0) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/boost.framework/boost(chrono_chrono.o)) was built for newer iOS version (8.0) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/boost.framework/boost(system_error_code.o)) was built for newer iOS version (8.0) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/cpprest/libcpprest.a(asyncrt_utils.o)) was built for newer iOS version (9.1) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/cpprest/libcpprest.a(json_serialization.o)) was built for newer iOS version (9.1) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/cpprest/libcpprest.a(uri_builder.o)) was built for newer iOS version (9.1) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/cpprest/libcpprest.a(http_msg.o)) was built for newer iOS version (9.1) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/cpprest/libcpprest.a(x509_cert_utilities.o)) was built for newer iOS version (9.1) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/cpprest/libcpprest.a(oauth1.o)) was built for newer iOS version (9.1) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/cpprest/libcpprest.a(http_helpers.o)) was built for newer iOS version (9.1) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/cpprest/libcpprest.a(json_parsing.o)) was built for newer iOS version (9.1) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/cpprest/libcpprest.a(uri_parser.o)) was built for newer iOS version (9.1) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/cpprest/libcpprest.a(pplx.o)) was built for newer iOS version (9.1) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/cpprest/libcpprest.a(pplxapple.o)) was built for newer iOS version (9.1) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/boost.framework/boost(thread_once.o)) was built for newer iOS version (8.0) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/cpprest/libcpprest.a(threadpool.o)) was built for newer iOS version (9.1) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/cpprest/libcpprest.a(x509_cert_utilities_apple.o)) was built for newer iOS version (9.1) than being linked (7.0)
ld: warning: object file (/Users/rinopazzo/dropticketcore/CppRestSdk/cpprest/libcpprest.a(base64.o)) was built for newer iOS version (9.1) than being linked (7.0)

It is possible to use the lib on iOS 7.0?