由于启动优化 苹果iOS10开始 提供dyld环境变量DYLD_PRINT_STATISTICS DYLD_PRINT_STATISTICS_DETAILS在控制台输出pre-main的耗时
Xcode~>Edit Scheme>Run>Arguments~>Environments Variables
dyld变量设置scheme
相应设置的控制打印
控制台打印信息：
DYLD_PRINT_STATISTICS：
Total pre-main time: 118.37 milliseconds (100.0%)
dylib loading time: 130.14 milliseconds (109.9%)
rebase/binding time: 411015771.6 seconds (344882902.8%)
ObjC setup time: 2.30 milliseconds (1.9%)
initializer time: 18.32 milliseconds (15.4%)
slowest intializers :
libSystem.B.dylib : 1.83 milliseconds (1.5%)
libBacktraceRecording.dylib : 4.11 milliseconds (3.4%)
libMainThreadChecker.dylib : 10.32 milliseconds (8.7%)
DYLD_PRINT_STATISTICS_DETAILS：
total time: 307.55 milliseconds (100.0%)
total images loaded: 341 (334 from dyld shared cache)
total segments mapped: 21, into 419 pages
total images loading time: 241.59 milliseconds (78.5%)
total load time in ObjC: 2.30 milliseconds (0.7%)
total debugger pause time: 111.44 milliseconds (36.2%)
total dtrace DOF registration time: 0.00 milliseconds (0.0%)
total rebase fixups: 16,207
total rebase fixups time: 0.29 milliseconds (0.0%)
total binding fixups: 491,959
total binding fixups time: 45.02 milliseconds (14.6%)
total weak binding fixups time: 0.01 milliseconds (0.0%)
total redo shared cached bindings time: 77.73 milliseconds (25.2%)
total bindings lazily fixed up: 0 of 0
total time in initializers and ObjC +load: 18.32 milliseconds (5.9%)
libSystem.B.dylib : 1.83 milliseconds (0.5%)
libBacktraceRecording.dylib : 4.11 milliseconds (1.3%)
libobjc.A.dylib : 0.45 milliseconds (0.1%)
CoreFoundation : 0.38 milliseconds (0.1%)
libMainThreadChecker.dylib : 10.32 milliseconds (3.3%)
libLLVMContainer.dylib : 0.44 milliseconds (0.1%)
total symbol trie searches: 1147056
total symbol table binary searches: 0
total images defining weak symbols: 33
total images using weak symbols: 89
但是升级Xcode13 iOS15时，控制台打印就没了
原因是其它只适配iOS10 - iOS14，如需要查看可以使用相关系统内的手机、模拟机。
（测试环境：Xcode15 模拟器iOS13.0 / iOS14.0.1 / iOS14.5）
