why iphone color going crazy on viewing and exporting ?

Without any details, it's hard to give specific help. And you provided no details of what you're doing, and what your color management settings are within Premiere, and on what hardware. Nothing useful.

So in generalities ... almost everyone with problems with iPhone media is having one of two problems, or at times, both.

The first ... they haven't properly set their color management settings in Premiere. If the settings were correct, there wouldn't be the problem they were having.

The second ... is Apple's broken (by design) color management utility ColorSync, which was designed to use the camera transform function ... essentially gamma 1.96 ... as the display transform function. And apparently, from some high-end colorist testing, does a poor job of mapping sRGB data to the P3 color space of the Retina monitors on top of the gamma issue.

The Rec.709 video display transform is long standing, and by the standard, is essentially gamma 2.4. There is no reason nor excuse for this mess. I work for/with/teach pro colorists, mostly based in Resolve, many of them total Mac geeks, and they are furious with Apple over this crud.

The lifted gamma means the shadows and midtones are lighter in QuickTime player, Chrome and Safari browsers, than in Premiere ... or all non-Mac systems. Including those set to broadcast specs.

But it's even richer ... because on Macs with Reference modes, set to HDTTV, the correct display gamma is used!

So it's only Mac users without Reference modes that Apple stuck with the issue. Oh ... joy.

Premiere Color Management ... AGAIN.

Set Display color managment, auto detect log, auto tonemapping to on. Use a Rec.709 sequence color space, and export ONLY using export presets that do not have HLG or PQ in the preset name.

This will give you a solid SDR/Rec.709 working process.

By the way, color management in the 25.x series that will 'ship' probably first day of Adobe MAX in October, is already in the public beta. And it much more complex and capable than the current CM stuff. You'll need to learn more ... but it is a huge overall improvement.

Viewing Gamma Settings in Premiere

There are several things you can choose here, and it's partly pick your poison if you are worried about Macs without reference modes.

Only worried about Macs without Reference modes?

Then set the Viewing Gamma to 1.96/QuickTime. And do your color corrections.

1) Outside of Premiere on Macs without Reference Modes ... but only in QuickTime Player, Chrome and Safari browsers: the image will be like what it is inside Premiere.

2) On ALL other systems ... including Macs with Reference modes set to HDTV, all broadcast compliant systems, most PCs, Androids, and TVs, the image will be too dark and probably oversaturated.

Yea ... pick your poison. But what about "normal" working, and choosing how to set viewer gamma?

Viewer gamma decisions should  be based on your working ambient environment while grading.

Professional colorists have very specific working requirements. A nearly darkened room, gray surround behind the monitor with a slight "bias" light (lighting the wall behind the monitor) of specified reflectivity "visually" around the reference monitor, with monitor carefully fed a signal from a breakout device from BlackMagic or AJA (NEVER from the GPU).

The monitor itself is both calibrated to Rec.709 specs ... sRGB color space, 100 nits max brightness, D65 white point, (essentially) gamma 2.4. And then a profile pass is made, to verify the performance of the monitor within strict limitations.

If you are working in a darkened room with a monitor of max 100 nits brightness, you should choose Viewing Gamma of 2.4

If you are working in a moderately bright to bright room, and the monitor is above 100 nits brightness ...  then you should set the Viewing Gamma in Premiere to gamma 2.2/web.

And the vast majority of current monitors, even when using the monitor's Rec.709 settings, will be somewhere between 220 nits to 400 nits brightness. WAY above the actual Rec.709 specs.