Qt错误：错误：找不到架构x86_64

Question

我想在Qt Creator中创建一个简单的项目，但我无法运行它。

#include <QApplication>
#include <QLabel>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QLabel label("Hello, world");
    label.show();

    return app.exec();
}

这是我的.pro

#-------------------------------------------------
#
# Project created by QtCreator 2017-08-03T16:29:59
#
#-------------------------------------------------

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = Hello
TEMPLATE = app

# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0


SOURCES += \
        main.cpp \
        mainwindow.cpp

HEADERS += \
        mainwindow.h

我是qt的绝对新生，我只是按照互联网上的一些课程，所以我不知道它有什么问题。我的mac os：10.12.3。 Qt Creator：4.3.1基于Qt 5.9.1（Clang 7.0（Apple），64位）