查看APP启动时间

Edit Scheme > Run > Arguments > Environment Variables

添加变量 Name DYLD_PRINT_STATISTICS Value 设置为 YES

启动时间统计

可以看到APP在执行main 函数之前的操作花费的时间

Total pre-main time: 158.84 milliseconds (100.0%)
         dylib loading time:  54.81 milliseconds (34.5%)
        rebase/binding time:  29.42 milliseconds (18.5%)
            ObjC setup time:  47.20 milliseconds (29.7%)
           initializer time:  27.23 milliseconds (17.1%)
           slowest intializers :
             libSystem.B.dylib :   2.49 milliseconds (1.5%)
    libMainThreadChecker.dylib :  14.97 milliseconds (9.4%)