Bump travis ci to use xcode 12

[jjatie]

This is just to bump travis to use the latest Swift compiler. Project changes for Xcode 12 will come in a separate PR

[liuxuan30]

*** Checking out ios-snapshot-test-case at "6.2.0"
*** Cloning ios-snapshot-test-case
*** xcodebuild output can be found in /var/folders/z3/_825pg0s3jvf0hb_q8kzmg5h0000gn/T/carthage-xcodebuild.iiamXF.log
*** Downloading ios-snapshot-test-case.framework binary at "6.2.0"
***  Skipped installing ios-snapshot-test-case.framework binary due to the error:
	"Incompatible Swift version - framework was built with 5.1 (swiftlang-1100.0.270.13 clang-1100.0.33.7) and the local version is 5.3 (swiftlang-1200.0.29.2 clang-1200.0.30.1)."

ios-snapshot-test-case is not updated so the binary framework failed. I checked there is no new update on their repo. So seems we have to build from scratch to avoid this at least for now

[liuxuan30]

@jjatie seems the problem is Carthage after changing to source compile. Carthage/Carthage#3019

there is a workaround mentioned here

Workaround that works with both Xcode 11 and 12

Works with all versions of Xcode 12 (except beta 1 and 2; but no-one should be using those anymore). Once XCFrameworks support lands in Carthage this workaround won’t be needed. However not that XCFrameworks puts some strict requirements on projects that most projects don’t comply with.

Note: This is a change from before where the script excluded arm64 for simulators by individual Xcode 12 version. It now removes it from all Xcode 12 based builds.

How to use

Save the script (👇) to your project (e.g. as a carthage.sh file).
Make the script executable chmod +x carthage.sh
Instead of calling carthage ... call ./carthage.sh ...
E.g. ./carthage.sh build or ./carthage.sh update --use-submodules

Script

#!/usr/bin/env bash

# carthage.sh
# Usage example: ./carthage.sh build --platform iOS

set -euo pipefail

xcconfig=$(mktemp /tmp/static.xcconfig.XXXXXX)
trap 'rm -f "$xcconfig"' INT TERM HUP EXIT

# For Xcode 12 make sure EXCLUDED_ARCHS is set to arm architectures otherwise
# the build will fail on lipo due to duplicate architectures.
echo 'EXCLUDED_ARCHS__EFFECTIVE_PLATFORM_SUFFIX_simulator__NATIVE_ARCH_64_BIT_x86_64__XCODE_1200 = arm64 arm64e armv7 armv7s armv6 armv8' >> $xcconfig
echo 'EXCLUDED_ARCHS = $(inherited) $(EXCLUDED_ARCHS__EFFECTIVE_PLATFORM_SUFFIX_$(EFFECTIVE_PLATFORM_SUFFIX)__NATIVE_ARCH_64_BIT_$(NATIVE_ARCH_64_BIT)__XCODE_$(XCODE_VERSION_MAJOR))' >> $xcconfig

export XCODE_XCCONFIG_FILE="$xcconfig"
carthage "$@"

[liuxuan30]

@jjatie I'm having a hard time on my side that most of the tests failed even in the Xcode itself.
I'm seeing the failures because image diff exceeds the tolerance. however I couldn't say who's fault. (likely Apple?)

for example, the diff image on my side is (bold area is the image diff):

I also roll back to my commit fix line chart UT failures, it still fails. so I think this might because of the new iOS14 SDK? I'm on Xcode 12.0.1 right now.

could you try it on your side to see what will happen?

if you got similar issues like me, do you think this is a bug and we should report to apple, or we just recreate new images?

[liuxuan30]

I have made the image refresh a single commit so we can move on or revert. I'm really confused, but seems there is some hidden changes in the UIKit or CoreGraphics rendering component that causes the slight difference.
@jjatie I still need you to help to take a look at old images and have consistent behaviours like me. thank you

[liuxuan30]

let's move ahead